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

app/javascript/styles/mastodon/components.scss

@@ -1592,6 +1592,10 @@ a.account__display-name {
   color: $gold-star;
 }
 
+.bookmark-icon.active {
+  color: $red-bookmark;
+}
+
 .no-reduce-motion .icon-button.star-icon {
   &.activate {
     & > .fa-star {

app/javascript/styles/mastodon/variables.scss

@@ -6,6 +6,8 @@ $error-red: #df405a !default;        // Cerise
 $warning-red: #ff5050 !default;      // Sunset Orange
 $gold-star: #ca8f04 !default;        // Dark Goldenrod
 
+$red-bookmark: $warning-red;
+
 // Values from the classic Mastodon UI
 $classic-base-color: #282c37;         // Midnight Express
 $classic-primary-color: #9baec8;      // Echo Blue