This commit adds a new Revise... action that can be taken
for queued post reviewables. This will open a modal where
the user can select a Reason from a preconfigured list
(or by choosing Other..., a custom reason) and provide feedback
to the user about their post.
The post will be rejected still, but a PM will also be sent to
the user so they have an opportunity to improve their post when
they resubmit it.
Performing a `Delete User`/`Delete and Block User` reviewable actions for a
queued post reviewable from the `review.show` route results in an error
popup even if the action completes successfully.
This happens because unlike other reviewable types, a user delete action
on a queued post reviewable results in the deletion of the reviewable
itself. A subsequent attempt to reload the reviewable record results in
404. The deletion happens as part of the call to `UserDestroyer` which
includes a step for destroying reviewables created by the user being
destroyed. At the root of this is the creator of the queued post
being set as the creator of the reviewable as instead of the system
user.
This change assigns the creator of the reviewable to the system user and
uses the more approapriate `target_created_by` column for the creator of the
post being queued.
