Merge branch 'master' into glitch-soc/merge-upstream

Conflicts:
- app/controllers/admin/base_controller.rb
- app/controllers/filters_controller.rb
- app/controllers/invites_controller.rb
- app/controllers/settings/deletes_controller.rb
- app/controllers/settings/exports_controller.rb
- app/controllers/settings/follower_domains_controller.rb
- app/controllers/settings/migrations_controller.rb
- app/controllers/settings/notifications_controller.rb
- app/controllers/settings/preferences_controller.rb
- app/controllers/settings/two_factor_authentication/recovery_codes_controller.rb
- app/javascript/packs/public.js
- app/views/settings/profiles/show.html.haml

Conflicts were mostly due to the addition of body classes to the settings page,
this was caused by rejecting upstream changes for most of those files and
modifying Settings::BaseController instead.

Another cause of conflicts was the deletion of client-side checking of
display name / bio length, this was modified in app/javascript/core/settings.js
instead.

lib/mastodon/version.rb

@@ -21,7 +21,7 @@ module Mastodon
     end
 
     def flags
-      'rc1'
+      'rc2'
     end
 
     def to_a