install: support pre-commit util

[efiop]

So far looks like we only need pre-commit to add support for post-checkout hook. Authors are ok with implementing it pre-commit/pre-commit#1120 and the implementation is pretty straightforward. Might consider contributing that to provide the best experience for the users (as our dvc hooks get into conflict with out pre-commit hooks already).

[andrewhare]

I'm beginning work on this ticket now.

[andrewhare]

I've written up two PRs for pre-commit:

• Add post-checkout pre-commit/pre-commit#1339
• Add docs for post-checkout pre-commit/pre-commit.com#307