Consider adding parser.c to .gitignore

[gjsjohnmurray]

Reasons:

• They are huge.
• They each start with a comment which varies depending on which exact version of tree-sitter a dev is using
• Tree-sitter 1.0 Checklist tree-sitter/tree-sitter#930 (comment)

[davem-intersys]

After a bit of research, it seems that the parser.c (and some of the other generated files) are somewhat necessary:

• Down-stream consumers: Tools like nvim-treesitter, Zed, emacs, Helix, etc. typically clone grammar repositories and compile the parser.c directly.
• Version compatibility/Deterministic builds: The generated parser is tied to a specific tree-sitter CLI version; committing it ensures everyone gets a parser generated with the same version we tested with.
• Faster/easier installation: No need for tree-sitter tooling to be installed.
• Standard practice: It seems that most if not all tree-sitter grammars in the wild commit their generated files.

In commit 7a55bbf, I did just add -diff to the generated files listed in .gitattributes that should at least trigger Github not to show the diffs for these large, generated files.

This is definitely something we can revisit if/when the tree-sitter tooling evolves to the point where it's not necessary to include this.