Add bookmarks (#7107)

* Add backend support for bookmarks

Bookmarks behave like favourites, except they aren't shared with other
users and do not have an associated counter.

* Add spec for bookmark endpoints

* Add front-end support for bookmarks

* Introduce OAuth scopes for bookmarks

* Add bookmarks to archive takeout

* Fix migration

* Coding style fixes

* Fix rebase issue

* Update bookmarked_statuses to latest UI changes

* Update bookmark actions to properly reflect status changes in state

* Add bookmarks item to single-column layout

* Make active bookmarks red

config/routes.rb

@@ -289,6 +289,9 @@ Rails.application.routes.draw do
           resource :favourite, only: :create
           post :unfavourite, to: 'favourites#destroy'
 
+          resource :bookmark, only: :create
+          post :unbookmark, to: 'bookmarks#destroy'
+
           resource :mute, only: :create
           post :unmute, to: 'mutes#destroy'
 
@@ -324,6 +327,7 @@ Rails.application.routes.draw do
       resources :blocks,       only: [:index]
       resources :mutes,        only: [:index]
       resources :favourites,   only: [:index]
+      resources :bookmarks,    only: [:index]
       resources :reports,      only: [:create]
       resources :trends,       only: [:index]
       resources :filters,      only: [:index, :create, :show, :update, :destroy]