MBS-6401: Restore ordering of release group artwork
MBS-6486: ModBot should remove collaboration relationships on AC split

f0b7974de504d3b07 changed the call to edit_action for Artist->split to have to
entries for on_creation. As such, the latest definition wins (because the
arguments to on_creation are a mapping and there can only be one entry per key).

This commit merges both on_creation entries into a single entry, and also adds a
test to ensure that behaviour is correct.
MBS-6401: Actually test ordering is by release date
MBS-4671: Enter 'remove collaboration relationship' edits as original editor
mbs-6531: add not_found page to areas
MBS-6426: Accept Edit::Release::Edit edits that delete release events

When accepting the edit, if we have a release event of the form
"<country: null, date: null>" simply omit inserting this release event.
Release events are inserted as a full set replacement, so this acts
like deletion.

This is needed to accept some old pre-schema-17 edits.
MBS-6426: Do not destroy release events when editing other release information

The merge implementation would always set $merged->{events} to $new->{events},
even if this key didn't exist in $new. This would leave $merged->{events} as
`undef`, but unfortunately autovivification means that this gets inflated to []
in the `grep` introduced in the parent commit.  As such, Release->update would
interpret this as clearing all release events for a release.

This commit displays setting $merged->{events} in this case.
mbs-6413: add text if there are no releases for an area
mbs-6414: remove cruft from wikidata URLs
MBS-6369: Add area bubbles to artist/label forms

Adds "you selected..." bubbles to all areas fields in edit/create
artist/label forms. I've had to capture the area.gid value so that
the edit forms are able to link to the selected area if the rest of
the form does not validate.
MBS-6275: Attempt to correlate changed release events in edits

Now tries to match old and new release events that have the same
country. In the case that they do, we use a full character diff to
display the exact differences. For remaining events that don't have
a common country on both sides of the diff, we list all countries.
MBS-6498: Support unformatting submillisecond durations

Some historic edits have durations such as 93.3333 ms (#8152338)
which cause the site to crash when attempting to display these. This
commit changes UnformatTrackLength to be able to parse this, and
truncates this number to an integer.
MBS-6454: <Enter> should submit edit relationship type page

Uses setDefaultAction() to make sure that the final submit button
is the default button for submitting the form.
Merge branch 'mbs-6486' into beta
Merge branch 'mbs-6275' into beta
Merge branch 'mbs-6369' into beta
Merge branch 'mbs-6401' into beta
Merge remote-tracking branch 'reosarevok/mbs-6413' into beta
Merge remote-tracking branch 'reosarevok/mbs-6414' into beta
Merge branch 'mbs-6426' into beta