Remove UserTypes, -Consts, and -Fns in favor of their Package equivalents

[StachuDotNet]

• removes
  • FQTypeName.Package, UserType
  • FQConstantName.Package, UserConstant
  • FQFnName.Package, UserFn
  • the ability to store those^ in our SQL DB
• anywhere where those things were used, the Package equivalents are now used
• as such, the "Program" type in RuntimeTypes became a lot thinner
• tidies both F# and Dark NameResolvers accordingly
• backfills some Dark WrittenTypesToDark work, along with some ProgramTypes pretty-printing
• tidies Dark Builtin.debug to behave more like the debuG we have in F#
• renames SourceRange to Range in a few places, as I noticed some tests were failing

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This is towards a larger effort in Package Manager work.

• The next step is to have PT and RT type/const/fn references work by-hash rather than by-name, forcing name-resolution to happen always at parse-time.
• After that, we can do a more notable PM refactor, following the footsteps of DONOTMERGE: sketching PM and PM Pre-work #5353 and experiment: support VS Code TreeView with lang. server #5345

[StachuDotNet]

note to self: remember to test that the CLI is still working alright

[StachuDotNet]

the TODOs outlined above are the only remaining work here - planning on wrapping this up sometime tomorrow