Extend `avoid-accidental-submissions` to include quick paste + cmd-enter submissions #4670

Description

Ever pasted the wrong thing in a field and then submitted it immediately after? It happens rarely but… we could:

• prevent cmd-enter/ctrl-enter right after a paste event (wait at least 500ms)

https://user-images.githubusercontent.com/1402241/129486125-e39e7b5d-ea2e-4691-8aa6-0c3a6b9ea223.mov

Note:

• Since cmd-enter works in any field and textarea it might be a little difficult to show a message in the right place
• It feels like this should be OS-wide thing but perhaps we can implement it here

Example URL

Any page with a form or just hasComments