BuildBuddy GitHub app: Submodules

[ivucica]

Hello!

I have a toy project repo where I've quasi-vendored a few other rules repos by adding them as Git submodules, and then using WORKSPACE rules to pull them in via local_repository().

These are perfectly usable with GitHub Actions, but if I get the BuildBuddy GH app to run bazelisk et al, it doesn't check out the submodules first. I haven't spotted a way to make it do so.

While I could by now switch over to pulling them in via a HTTP archive (perhaps write a wrapper repo rule that falls back to that approach if the submodule is not checked out, or write a wrapper rule that runs git submodule update --init if the submodule is not checked out), it would be a useful feature in BuildBuddy as well.

[sluongng]

I would recommend using git_repository instead of local_repository and git submodule as Bazel will lazily fetch the git repositories only when they are needed for the build.

Our BuildBuddy Workflows should work with git_repository today. There is a small bug reported this week that would prevent using git_repository on private repos, we are actively working on a fix for this.

@ivucica could you switch from using git submodule to git_repository?