MBS-5587: When displaying release group coverart, use the caa.org/release-group/ endpoint, not the release one.
MBS-4981/MBS-6563: correctly use cover_art_presence and the existence of a front image for a release
MBS-4981/MBS-6563: amend messages
MBS-6608: require auth for artist split page
MBS-5587: switch to Artwork::Release/Artwork::ReleaseGroup objects
MBS-5587: deduplicate release/release_id and provide a default implementation of _urlprefix
MBS-5587: remove Artwork::Release.
MBS-6608: have Edit imply RequireAuth
MBS-6608: remove extraneous RequireAuth and correct to use simply Edit
MBS-3823: Limit buttons to only Parse Tracks and Close in track parser
Merge branch 'mbs-3823' into beta

* mbs-3823:
  MBS-3823: Limit buttons to only Parse Tracks and Close in track parser
Merge branch 'mbs-4981-6563-coverart-presence' into beta

* mbs-4981-6563-coverart-presence:
  MBS-4981/MBS-6563: amend messages
  MBS-4981/MBS-6563: correctly use cover_art_presence and the existence of a front image for a release
Merge branch 'mbs-5587-rg-coverart-urls' into beta

* mbs-5587-rg-coverart-urls:
  MBS-5587: remove Artwork::Release.
  MBS-5587: deduplicate release/release_id and provide a default implementation of _urlprefix
  MBS-5587: switch to Artwork::Release/Artwork::ReleaseGroup objects
  MBS-5587: When displaying release group coverart, use the caa.org/release-group/ endpoint, not the release one.
Merge branch 'mbs-6608' into beta

* mbs-6608:
  MBS-6608: remove extraneous RequireAuth and correct to use simply Edit
  MBS-6608: have Edit imply RequireAuth
  MBS-6608: require auth for artist split page