Support sublime-text git message

When editing commit message in sublime text, I had to do this config to make it work, in `language-ids.sublime-settings`:
```
{
"text.git.commit": "git-commit"
}
```

It would be nice to add that language in the list for git commit: `git` (sublime text send `"languageId": "git"`)

I think here: https://github.com/Automattic/harper/blob/515a97b7f93b4afbcfe138e80e79140a3faab133/harper-ls/src/backend.rs#L364

Start at harper-ls/src/backend.rs around line 364 and inspect the list of language IDs recognized for Git commit messages. Add Sublime Text's "git" language ID to that list, then verify that commit messages reporting languageId "git" are recognized.

Written by the indexing model from the issue text.