Co-authored-by: Michael Davis <mcarsondavis@gmail.com>

This is an implementation for helix-editor#3346.

Previously, one of the following runtime directories were used:

1. `$HELIX_RUNTIME`
2. sibling directory to `$CARGO_MANIFEST_DIR`
3. subdirectory of user config directory
4. subdirectory of path to helix executable

The first directory provided / found to exist in this order was used as a
root for all runtime file searches (grammars, themes, queries).

This change lowers the priority of `$HELIX_RUNTIME` so that the user
config runtime has higher priority. More significantly, all of these
directories are now searched for runtime files, enabling a user to override
default or system-level runtime files. If the same file name appears
in multiple runtime directories, the following priority is now used:

1. sibling directory to `$CARGO_MANIFEST_DIR`
2. subdirectory of user config directory
3. `$HELIX_RUNTIME`
4. subdirectory of path to helix executable

One exception to this rule is that a user can have a `themes`
directory directly in the user config directory that has higher piority
to `themes` directories in runtime directories. That behaviour has been
preserved.

As part of implementing this feature `theme::Loader` was simplified
and the cycle detection logic of the theme inheritance was improved to
cover more cases and to be more explicit.

Was not implemented correctly as the order was
in the most cases assigned from the values of
an HashMap, which does not guarantee order.
This applied to when a keymap was both
deserialized and merged.

Info box body was then being sorted as a
function of the fallacious `order` property,
and by a method that yielded at worst a time
complexity of at least n^2.

Furthermore, the body contents were inerted
at first by the order of the hash map keys,
in which `order` itself was based on.

A more reliable predifined sorting order is to be
implemented.

Exist under the wrong (possibly just outdated)
assumption that command descriptions are written
with their KeyTrie name prefixed (Space, View,
Goto etc.). For examle: The command `file_picker`
is assumed to have the description
"Space Open file picker", which is not the case
, nor for any other command description.

BTree was being used to store a list of keyevents
for a given command. This list was only iterated
over twice to in the end be converted to a Vec.

Better to just use a Vec from start given the use-
case. Temporalily reverts helix-editor#952.

Infobox body was being filled with description
then KeyEvent list to only later be iterated over
for the purpose of flippingin this order.

Vec<KeyEvent> was being created as an
intermediary into Info.rs for it to be
converted into a comma separated string.

This commit removes this intermediate step
but also the single purpose from_keymap
public function in Info.rs, as it is no
longer needed.

* Descriptive naming and correct use of data structure terminology
  example translations:
    keymap.reverse_map -> keymap.command_list
    keytrienode -> keytrie (struct)
      search->traverse
      merge->merge_keytrie
    keytrie -> keytrienode (enum describing node variants)
      Leaf -> MappableCommand
      Sequence -> CommandSequence
      Node -> KeyTrie
      (A leaf is a node, and the sequence was also a node.
	  So old naming made absolutely no sense whatsoever.)
* Splitting parts of the keymap.rs file into
  {keytrienode, keytrie, keymaps, tests}.rs.
  (Should be self-explanatory by looking at the old keymap.rs.)
* Removed KeytrieNode enum functions node(&self) -> Option<&KeyTrie>
  and node_mut(&mut self) -> Option<&mut KeyTrie> from KeyTrieNode
  as they served no purpose that could not be used from elsewhere.
  Was also a bit strange to return a "parent struct" from an enum
  "building block".
* Removed getters that could be achieved by making fields public for
  now. (E.g .root(), .map(), .name())
* Removed keymap.merge() and keytrienode.merge_nodes()
  All merging could be handled by keytrie.merge() and
  keymaps.merge_with_default(), unnecessary to have a second
  unused system that does about the same thing.
  We also don't want functions that can cause panics as
  merge_nodes() could.
* Initial simplification and formatting of command palette.
  Formatting is done during the creation of the command lists,
  removes the need for the creation and and traversal of an
  intermediary Vec<Vec<String>>.
  Keyevent formatting changed from "(<space>w<C-q>)" to ["space>w>C-q"].
  Clarifying how commands are triggered by moving through
  submenus/keytries.

For it not to be confused with the upcoming ":help"
feature.

This, along with previous commit reverts regression in helix-editor#952

Sort duration calculations averaged to about
0.04 ms when opening the larger infoboxes.

* Elaborated on test descriptions
* Removed duplicate unit test
* Unified keytrie traversal in tests

* Moved config merging Keymaps to Config
* Removed unused default EditorView function

It produces, after all, a Keytrie. It would
be a bit like saying: let engine = car!()

By the end of this refactroring
it became clear that it was mostly
acting as a useless wrapper for
KeyTrie.

Root keymap module was empty as old Keymap
could be removed. And there was no point
anymore in differentiating Keymaps and
Keymap.

* Fixed aliased_modes_are_same_in_default_keymap to check for order too.
  It failed to detect a bug in which the swap_view_* were ordered differently
  under space-w and c-w.

Sorts by modifier, then by KeyCode category, then by each KeyEvent.
Single character alphas are placed before the rest (ex. "space") in KeyCode::Char.

* Renamed helix_core::syntax::Configuration to
LanguageConfigurations to dinstiuish it from the other
types of configurations (theme, keys, editor...),
and to illustate that it is actually a collection of
LanguageConfigurations

* (Would similarly want the the LanguagesConfiguarions field
'language' was renamed to 'language_configurations' but that
wold interfere with the languages.toml file.

* Renamed user_lang_config to merged_lang_config, as it includes the default language config.

* Moved the functions of helix_loader::config (relate only
to langage config) to helix-loader/lib.rs, and removed
the file. Mostly to aid in comparison in how the config
is loaded.

* Moved the functions of helix_core::config to
helix_core::syntax. This way they're loaded the same way as
the config.toml. Forces a consistency initialsing language
config with LanguageConfigurations::default() and ::merged()
respectively. helix_core::config.rs was then removed.

* Removed config dir check and creation from helix-term main.rs, it
  was being done in the proceeding line with helix_loader::initialize_config_file()
* Log path setup moved to helix_loader, and setup not done before setting up logging.
  It would create the default log folder even if user specifies thier own log file.
* Fixed helix_loader::config_file() and log_file() assumption of existing parent directory.

Return Ok(0) to main instead of directly doing
process::exit(0) on only some of the args. Makes
it easier to implement special exit handling
before quitting.

Does not put project in working state,
rebase with helix-editor#5635

…config

…config

* RUNTIME_DIR now behaves similar to the other
  runtime files
* merge_toml_values: Moved function explanation
  comment in a function call to its
  documentation.

* Wider use relative path replacements by moving xtask::pash to  helix_loader::repo_paths.rs.
* Wider use of new LanguageConfig load API
* Minor appalication.rs cleanup

health.rs
* Removed duplicate clipboard provider writeout.
* Removed 'all' flag option but added a 'paths' option.
* Removed check if user config exist or show default
  part as default is always merged with user config.

docgen:
* removed xtask::helper::lang_config(), using
  LanguageConfiguarions::default() instead.
* moved xtask::query_check to xtask::main and made it use
  TSFeature.runtime_filename()

…fig' into unify-config

* Fix failing integration testing
* Fix bug in which which local directories were being tested for their
  existence.
* Fixes helix-editor#5144
* Ran cargo fmt

…config

…config

…config

…config

…config

…into keymap-presentation

…config

Reduced comment some verbosity, the method
signatures should speak for themselves.

runtime_file -> get_runtime_file

…th")

* Clarify method signature of newly intrudused path -> find_remaining_path
* Remove unused self.names()
* Removed overly verbose comments.

Replaces the get_runtime_dirs().first().expect("...") in helix_loader:::grammar