Add tree-sitter injections for jj config files

[bryceberger]

The config file for jj has some tables that canonically contain a few domain-specific languages: all keys in [revsets] and [revset-aliases] are revsets, and similar for templates in [templates] and [template-aliases].

This injects those languages where appropriate.

[bryceberger]

I assumed unconditionally injecting based on the table name was appropriate, given the same is done in yaml/injections.scm for GitHub/GitLab/Buildkit CI.

If that's not appropriate, I can change it. One option would be to detect a top-level "$schema" = "https://jj-vcs.github.io/jj/prerelease/config-schema.json", or similar.

[kpbaks]

I assumed unconditionally injecting based on the table name was appropriate, given the same is done in yaml/injections.scm for GitHub/GitLab/Buildkit CI.

If that's not appropriate, I can change it. One option would be to detect a top-level "$schema" = "https://jj-vcs.github.io/jj/prerelease/config-schema.json", or similar.

Maybe we can make a specialisation for the file format, which uses the same toml grammar, similar to what is done in #13925, and have it be selected using file-types = [{glob = "..."}] selectors.

[the-mikedavis]

Yeah, injecting into all TOML isn't ideal. We should also consider splitting out the GitHub actions yaml injections into a separate language that globs for a .github directory which would reuse the yaml parser and add those injections.