Support getting the correct project root from a git submodule's COMMIT_EDITMSG

[mikavilpas]

I use https://github.com/mikavilpas/tsugit.nvim (lazygit) and sometimes work in projects that use git submodules. I want to use blink-ripgrep to write commit messages, so that I can reuse words in my project.

Currently the project root is resolved to the root of the main repo (with the submodules).
There is a performance problem in huge projects that contain many, many submodules.

Instead of resolving the root of the main repo, by default I think the submodule root should be used instead.

/Users/mikavilpas/git/root-repo/.git/modules/sub-repo/COMMIT_EDITMSG

[mikavilpas]

Git allows getting the repo root with git rev-parse --show-toplevel. Maybe this can be reused so I don't have to write my own resolution logic.

[github-actions]

This issue is stale because it has been open for 30 days with no activity.