1982 delegate reject actions to content actions too

[eviljeff]

Fixes: mozilla/addons#15306

Depends on #23004 & needs rebasing after that is merged.

Description

Implements the last remaining actions that could need a hold for 2nd level approval - version rejections.

Context

To ease implementation, I've focused on the simple case - the initial rejection of one or more versions - so ignored auto rejections and rejections that happen via blocks (and renamed the existing reject_multiple_versions function). Auto rejections don't need another hold because it was already considered when the initial decision was made; blocks have their own hold criteria. Follow-up work would be to continue migrating the remaining code that changes addon/version states in the reviewer tools to their equivalent ContentAction

Testing

tbd...

Checklist

• Add #ISSUENUM at the top of your PR to an existing open issue in the mozilla/addons repository.
• Successfully verified the change locally.
• The change is covered by automated tests, or otherwise indicated why doing so is unnecessary/impossible.
• Add before and after screenshots (Only for changes that impact the UI).
• Add or update relevant docs reflecting the changes made.