Report UI (end-user)

See #890 (closed)

• Reports options added for artist, album, track, account and playlist
• Report modal containing a form to submit the report:
  • Logged in user can report in any category
  • Anonymous users can report in all categories that are allowed in the moderation__unregistered_report_types

cc @funkwhale/reviewers-front @funkwhale/reviewers-python

Logged-in report example

Peek_2019-09-06_13-31

Anonymous report example

Peek_2019-09-06_13-32