Pull requests should have CI run against them

[brentleyjones]

Before #15 is done, and preferably for the first PR of the rewrite, we should have CI checks running on pull requests. We can probably use BuildBuddy Workflows and GitHub actions similar to rules_xcodeproj.

Some things that we should check (and not all of it needs to be there at the start):

• Unit tests
• Linting
• Commit message check
• Documentation check

[pepicrft]

@brentleyjones I'd be happy to take this one on, but I'd need some guidance on the Bazel side of things. Could you give me some pointers around what's the interface through Bazel?