FR: Add a pre-commit hook for YAML formatting

[IndrajeetPatil]

Creating an issue to track this, just so that we don't forget about it.

I was wondering if we should add a pre-commit hook for YAML formatting (and I remembered there weren’t any popularones at the time I checked last time) and I found the there is one by Google now and I might use it in the future (google/yamlfmt#58).

Originally posted by @lorenzwalthert in r-lib/styler#1042 (comment)

[lorenzwalthert]

Strictly speaking I would not add the hook here, because it would be hosted, but we would add it to our template file.

[lorenzwalthert]

https://github.com/google/yamlfmt requires go. I am not sure we want to add this requirement for our project. It would not affect anyone beyond the developers of {precommit} if we use it in our .pre-commit-config.yaml, only once we put it in the template that gets populared when precommit::use_precommit(), our users would have this requiremet too unless they remove it from their config file again.