RFR: 1683: The force push notifier needs an overhaul [v5]

[Erik Joelsson]

On Wed, 23 Nov 2022 20:03:20 GMT, Zhao Song <zsong at openjdk.org> wrote:

>> A user reported a bug related with the force-push notification. Erik investigated it and found the implementation of this notification should not be in the `PullRequestBranchNotifier`. Also, users preferred to not get force-push notification if the force-push happens when the pr is in draft state.
>> 
>> In this patch, the implementation of checking force-push and notifying user are moved to `CheckWorkItem`. Also, force-pushing or rebasing a draft pr will not warn user any more.
>
> Zhao Song has updated the pull request incrementally with one additional commit since the last revision:
> 
>   adjust comment

Marked as reviewed by erikj (Lead).

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PR: https://git.openjdk.org/skara/pull/1426