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/locales/doorkeeper.en.yml

@@ -125,6 +125,7 @@ en:
       read: read all your account's data
       read:accounts: see accounts information
       read:blocks: see your blocks
+      read:bookmarks: see your bookmarks
       read:favourites: see your favourites
       read:filters: see your filters
       read:follows: see your follows
@@ -137,6 +138,7 @@ en:
       write: modify all your account's data
       write:accounts: modify your profile
       write:blocks: block accounts and domains
+      write:bookmarks: bookmark statuses
       write:favourites: favourite statuses
       write:filters: create filters
       write:follows: follow people