Feat/32 check branch protection rulesets

[AlexAxthelm]

For discussion in Tech Review this week (@hodie @RMI-PACTA/developers )

This PR adds an action to check for the existence of GitHub Rulesets, as well as some sample rulesets (in the rulesets/ directory)

Rulesets are the successor to "Branch Protection Rules" and "Required Checks". For our purposes, the most important part is that "Branch Protection Rules" do not apply to repo admins (by default: whoever created the repo), which rulesets do.

The workflow added here is intended to be called from another repo, and by default, it will check that the "Protect Main" rule is in effect, which:

• Disallows deletion of main
• Disallows force pushes to main
• Disallows creating main
• Disallows pushing to main
• Requires Pull Requests to main have at least 1 approval, requires codeowner approval, dismisses stale reviews when new commits are added, and requires approval from someone other than the last committer to approve. (all roughly what we have now)

There is another ruleset example (not enabled by default), which requires certain R status checks to pass before the PR is eligible to merge.

[cjyetman]

I don't see anything glaringly, syntactically wrong here, but I think I don't fully understand how it works, so don't have much to say about it. If this is something that repo owners would implement in their repos by calling this action from an action in their repo, then maybe an example action (like other in this repo have) would be appropriate?

[AlexAxthelm]

then maybe an example action (like other in this repo have) would be appropriate?

Yep. Planning on getting a number of the general/housekeeping checks ready together soon in a default/example action.

[jdhoffa]

retroactively lgtm :-)

[MonikaFu]

does this require an action from me as a maintainer?

[jdhoffa]

does this require an action from me as a maintainer?

No action required.

At this stage all actions in the actions repo are optional. This may change, however not before (many long drawn-out) discussions with the Tech Team.

Certain actions might be useful to you (e.g. https://github.com/RMI-PACTA/actions/blob/main/examples/R.yml and https://github.com/RMI-PACTA/actions/blob/main/examples/issues.yml)

but they are entirely at the discretion of the maintainer.