* Split media cleanup from reject-media domain blocks to its own service

* Slightly improve ClearDomainMediaService error handling

* Lower DomainClearMediaWorker to lowest-priority queue

* Do not catch ActiveRecord::RecordNotFound in domain block workers

* Fix DomainBlockWorker spec labels

* Add some specs

* Change domain blocks to immediately mark accounts as suspended

Rather than doing so sequentially, account after account, while cleaning
their data. This doesn't change much about the time the block takes to
complete, but it immediately prevents interaction with the blocked domain,
while up to now, it would only be guaranteed when the process ends.

* Add database columns for adding notes to domain blocks/restrctions

* Add admin UI to set private and public comments when blocking a domain

* Add text for private and public comments on domain blocks

* Show domain block comments in admin UI

* Add comments to the domain block undo page

* Make UnblockDomainService more robust regarding upgraded domain blocks

* Allow editing domain blocks

* Rename button from “undo domain block” to “view domain block” in account admin UI

* Change test to unsilence silenced users from upgraded blocks