Make compile targets a subcommand instead of a flag

[janmasrovira]

Changes

The main goal of this pr is to remove the --target flag for juvix compile and use subcommands instead. The targets that are relevant to normal users are found in juvix compile --help. Targets that are relevant only to developers are found in juvix dev compile --help.

Below I list some of the changes in more detail.

Compile targets for user-facing languages

• juvix compile native
• juvix compile wasi. I wasn't sure how to call this: wasm, wasm32-wasi, etc. In the end I thought wasi was short and accurate, but we can change it.
• juvix compile vampir
• juvix compile anoma
• juvix compile cairo

New compile targets for internal languages

See juvix dev compile --help.

1. dev compile core has the same behaviour as dev core from-concrete. The dev core from-concrete is redundant at the moment.
2. dev compile tree compiles to Tree and prints the InfoTable to the output file wihout any additional checks.
3. dev compile reg compiles to Reg and prints the InfoTable to the output file wihout any additional checks.
4. dev compile asm compiles to Asm and prints the InfoTable to the output file wihout any additional checks.
5. 4. dev compile casm compiles to Asm and prints the Result to the output file wihout any additional checks. TODO: should the Result be printed or something else? At the moment the Result lacks a pretty instance.

Optional input file

1. The input file for commands that expect a .juvix file as input is now optional. If the argument is ommited, he main file given in the package.yaml will be used. This applies to the following commands:
   1. juvix compile [native|wasi|geb|vampir|anoma|cairo]
   2. juvix dev compile [core|reg|tree|casm|asm]
   3. juvix html
   4. juvix markdown.
   5. juvix dev internal [typecheck|pretty].
   6. juvix dev [parse|scope]
   7. juvix compile [native|wasi|geb|vampir|anoma|cairo]
   8. note that juvix format has not changed its behaviour.

Refactor some C-like compiler flags

Both juvix compile native and juvix compile wasi support --only-c (-C), --only-preprocess (-E), --only-assemble (-S). I propose to deviate from the gcc style and instead use a flag with a single argument:

• --cstage [source|preprocess|assembly|exec(default)]. I'm open to suggestions. For now, I've kept the legacy flags but marked them as deprecated in the help message.

Remove code duplication

I've tried to reduce code duplication. This is sometimes in tension with code readability so I've tried to find a good balance. I've tried to make it so we don't have to jump to many different files to understand what a single command is doing. I'm sure there is still room for improvement.

Other refactors

I've implemented other small refactors that I considered improved the quality of the code.

TODO/Future work

We should refactor commands (under compile dev) which still use module Commands.Extra.Compile and remove it.