Feature: Report improvements (#6967) (#7000)

* Implement Assignment of Reports (#6967)

* Change translation of admin.report.comment.label to "Report Comment" for clarity

As we'll soon add the ability for reports to have comments on them, this clarification makes sense.

* Implement notes for Reports

This enables moderators to leave comments about a report whilst they work on it

* Fix display of report moderation notes

* Allow reports to be reopened / marked as unresolved

* Redirect to reports listing upon resolution of report

* Implement "resolve with note" functionality

* Add inverse relationship for report notes

* Remove additional database querying when loading report notes

* Fix tests for reports

* Fix localisations for report notes / reports