feat: Add C# language support

[urbit-pilled]

/claim #438

PS: The tree-sitter-c-sharp submodule has introduced a new tree-sitter-language crate (https://crates.io/crates/tree-sitter-language) to decouple grammar parsing with the rest of tree-sitter. Unfortunately this is incompatible with tree-sitter-facade so I reverted the tree-sitter-language changes.

This is why the submodule doesn't point to the official tree-sitter-c-sharp repository.

[morgante]

Looks good, would just love a few more tests to award the bounty. Also please run this on a real C# repo and confirm it works.

[urbit-pilled]

Thanks for the review @morgante.
I'll add more tests, test it out on a real repo and add tests within LINQ queries when I get the time (hopefully later today or tomorrow)