Auto-close PRs that are force-pushed for Oppia and Oppia Android

[BenHenning]

Is your feature request related to a problem? Please describe.
The Oppia and Oppia Android repos currently permit force-pushing despite it being against developer policy.

Describe the solution you'd like
We ought to automatically close force-pushed PRs and leave a comment that points to the wiki to explain why it was closed (i.e. https://github.com/oppia/oppia-android/wiki/Making-a-code-change).

Describe alternatives you've considered
N/A

Additional context
None

[seanlip]

I think we should also do this on the Oppia-web repo, if we haven't already. /cc @vojtechjelinek @DubeySandeep @U8NWXD

[U8NWXD]

I agree that this would be good for oppia-web too

[vojtechjelinek]

Agreed, @gp201 would you have time to look into this?

[BenHenning]

To clarify: I didn't realize that this wasn't already enabled in Oppia web, so I've updated the PR description to be less confusing.