[CI] Notify llvm-gatekeepers team about "ready for merge" patches.

[bader]

I see 34 PRs (MLIR project PRs are excluded) which are approved by code owners. 8 of them pass CI check. Some them were approved weeks ago but have no attention from the gatekeepers team. To simplify the process, I suggest we add an automatic notification that patch is ready for merge, which will trigger on approve and status update changes (+ additional notification for forgotten patches i.e. if no action on "ready" PR for N days, ping again).

[KornevNikita]

Hi! There have been no updates for at least the last 60 days, though the ticket has assignee(s).

@aelovikov-intel, could I ask you to take one of the following actions? :)

• Please provide an update if you have any (or just a small comment if you don't have any yet).
• OR mark this issue with the 'confirmed' label if you have confirmed the problem/request and our team should work on it.
• OR close the issue if it has been resolved.
• OR take any other suitable action.

Thanks!

[aelovikov-intel]

I'm not looking into this.