Apparently some instances have local users with local ap_ids
that are marked as local: false. Needs more investigation into how
that happened.

In the meantime, the skeleton migration was patched to just ignore
all known ap ids, not just locals. Doesn't seem to slow down the migration
too much on patch.cx

Closes #1746

FollowingRelationship storage & performance optimizations

See merge request !2332

Prevents the possibility of re-registration, which allowed to read
DMs of the deleted account.

Also includes a migration that tries to find any already deleted
accounts and insert skeletons for them.

Closes pleroma/pleroma#1687

Every time someone tries to use it, it goes mad and tries to scrape the
entire fediverse for no visible reason, it's better to just remove it
than continue shipping it in it's current state.

idea acked by lain and feld on irc

Closes #1595 #1422

Related: #1616

Some of the actions used to have a user map as a subject, which was then
changed to an array of user maps. However instead of migrating old data
there was just a hack to transform it every time, moreover this hack
didn't include all possible actions, which resulted in crashes. This
commit fixes the crashes by introducing a proper database migration for old data.

Closes #1606

Once more, with feeling

- Removed Grouped Reports; API needs proper architecture/refactor
- Cannot set Tesla adapter in AdminFE as it's not safe yet
- Layout/rendering improvements

This reverts commit 6395ad94

and moving it from instance settings

[#1478] OAuth admin tweaks: enforced OAuth admin scopes usage by default, migrated existing OAuth records. Adjusted tests.

This reverts merge request !2055