Early-out when attempting to report already permabanned users

[zneix]

I think it's pointless to report someone, who's already permad from some chat. Yet I caught myself reporting some bad actors for the second time after they've already been banned due to a previous report.

On the other side maybe someone would want to report an already banned person (some sort of ban appeal?). Not sure, but I think this wouldn't make much sense and it's safe to reject reports in these cases.

[ALazyMeme]

Duplicate of #649