Add beluga (.bel) language with tests

[aubertc]

This PR adds support for recognizing the Beluga language, which is a proof assistant similar to e.g. Rocq (formely Coq) or Lean.

Summary:

• add .bel extension mapping and Beluga language definition (cf. documentation)
• strip full-line and inline Beluga comments
• added example file and corresponding test

[AlDanial]

thanks!

[aubertc]

No, thank you for developing such a nice tool, integrating this language was a breeze ;-)

[aubertc]

Note (to self / anyone trying to add a language to cloc): this file was obtained by doing something like

cloc --yaml tests/inputs/beluga.bel > test/outputs/beluga.bel.yaml

and then manually editing the .yaml file to add the report_file : ../outputs/beluga.bel.yaml line.

@AlDanial please let me know if there is a better way to do it, and I'll probably create a pull request documenting how to add a language to cloc.

[aubertc]

Also if there is a linter or style that is enforced, please let me know ;-)

[AlDanial]

I welcome a PR to add instructions to the README on how to add a new language. btw, I use

cloc --yaml tests/inputs/beluga.bel --out test/outputs/beluga.bel.yaml

There's no linter or style guide for cloc. Free form, but hopefully you'll apply common sense :)

[aubertc]

Thanks @AlDanial , this is done with #963