CI: restrict PRs from being unmarked as draft if CI is failing. Maintainer whitelist to bypass

[p0mvn]

Background

We should restrict PRs from being marked as ready. We should whitelist core maintainers to still be able to unmark for exceptional urgent cases.

I've been guilty of marking PR as ready early myself. However, I think it would be good to have this restriction since a lot of us get notifications on readiness and waste cycles on reviewing non-ready PRs or even approve something prematurely if looks acceptable on a cursory review. A reviewer should start reviewing only if PR is fully ready.

Acceptance Criteria

• CI cannot be marked as ready while CI is failing
• Whitelist to bypass and still be able to unmark and merge