* Break out nested relationship API keys
This closes#5856 by restoring the existing behavior of the `muting`
and `following` keys (returning booleans rather than truthy or false).
It adds `showing_reblogs` and `muting_notifications` keys:
* `showing_reblogs` returns true if:
1. You've requested to follow the user, with reblogs shown, or
2. You are following the user, with reblogs shown.
* `muting_notifications` returns true if you have muted the user and
their notifications as well.
* Rubocop fix
* Fix pulling reblog/mute status from relationships
I could swear this had passed tests before, but apparently not.
Works now.
* More test fixes
Really, you'd expect this to be more straightforward.