Add Civet language support

[TemRevil]

Description

Adds support for Civet, the TypeScript-superset language, per #8046 (labeled Add Language / Good First Issue). Includes the languages.yml entry with generated language_id, the official grammar as a submodule, three real-world samples, and the regenerated grammar list entry.

Checklist:

• I am adding a new language.
  • The extension of the new language is used in hundreds of repositories on GitHub.com.
    • Search results for each extension:
      • https://github.com/search?type=code&q=NOT+is%3Afork+path%3A*.civet+civet
  • I have included a real-world usage sample for all extensions added in this PR:
    • Sample source(s):
      • https://github.com/edemaine/texlish/blob/main/src/cli.civet (cli.civet)
      • https://github.com/DanielXMoore/Civet/blob/main/source/config.civet (config.civet)
      • https://github.com/DanielXMoore/Civet/blob/main/source/cache.civet (cache.civet)
    • Sample license(s): MIT (both source repositories)
  • I have included a syntax highlighting grammar: https://github.com/DanielXMoore/Civet (MIT; TextMate grammar at lsp/vscode/syntaxes/civet.json, scope source.civet)
  • I have added a color
    • Hex value: #202c36
    • Rationale: dominant color of the official Civet favicon/logo at civet.dev
  • I have updated the heuristics to distinguish my language from others using the same extension.
    • Not needed: .civet is not associated with any other language in languages.yml.

Test results on this branch (Linux, rake samples regenerated): test_language, test_blob (10232 assertions) and test_grammars all pass with 0 failures.

[lildude]

When you ran script/add-grammar, the repo's license should have been cached into a yaml file. We need that file in this PR.

[AustinGrey]

Using this search, it appears there are 1.9k civet files indexed so far. Which is close to the 2k threshold, but not yet there. The repos appear to be representative, coming from different authors, so that won't be a concern. Will have to keep an eye on the stats.

[TemRevil]

@lildude good catch, thank you. I'd added the submodule by hand and missed the two steps script/add-grammar normally does for me. Pushed 58f9922 which sorts the .gitmodules entry into place and runs licensed cache for the Civet grammar, so vendor/licenses/git_submodule/Civet.dep.yml is now in the PR. Let me know if anything else is missing.

@AustinGrey appreciate you actually checking the numbers, that's the right way to look at it. Happy to sit on this until it clears 2k if that's the bar, will keep an eye on it too.