add CI and tune up git config

[the-mikedavis]

few things here:

• github actions CI that runs tests and checks formatting on PRs and pushes
• some additions to the .gitignore for some tree-sitter generated files that are not usually checked in
• a .gitattributes that marks generated files as generated
  • this makes diffs to those files auto-collapse in PR/commit diffs
  • and it excludes them from linguist's language inference for the repo, so the repo will become "a javascript repo" according to linguist, rather than a C repo
• I ran the formatter (I forgot in #3 :sweat_smile:)

what do you think?

[J3RN]

Fantastic work! :100: Thank you! :tada: