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

Conflicts:
- app/controllers/directories_controller.rb
- app/controllers/settings/applications_controller.rb
- app/controllers/settings/base_controller.rb
- app/controllers/settings/deletes_controller.rb
- app/controllers/settings/exports_controller.rb
- app/controllers/settings/follower_domains_controller.rb
- app/controllers/settings/imports_controller.rb
- app/controllers/settings/migrations_controller.rb
- app/controllers/settings/notifications_controller.rb
- app/controllers/settings/preferences_controller.rb
- app/controllers/settings/sessions_controller.rb
- app/controllers/settings/two_factor_authentication/confirmations_controller.rb
- app/controllers/settings/two_factor_authentication/recovery_codes_controller.rb
- app/controllers/settings/two_factor_authentications_controller.rb

Conflicts were due to some refactoring already made in glitch-soc
when introducing flavours.

config/routes.rb

@@ -179,6 +179,7 @@ Rails.application.routes.draw do
         post :disable
         post :redownload
         post :remove_avatar
+        post :remove_header
         post :memorialize
       end