Keyword/phrase filtering (#7905)

* Add keyword filtering

    GET|POST       /api/v1/filters
    GET|PUT|DELETE /api/v1/filters/:id

- Irreversible filters can drop toots from home or notifications
- Other filters can hide toots through the client app
- Filters use a phrase valid in particular contexts, expiration

* Make sure expired filters don't get applied client-side

* Add missing API methods

* Remove "regex filter" from column settings

* Add tests

* Add test for FeedManager

* Add CustomFilter test

* Add UI for managing filters

* Add streaming API event to allow syncing filters

* Fix tests

app/javascript/mastodon/components/status.js

@@ -157,6 +157,21 @@ export default class Status extends ImmutablePureComponent {
       );
     }
 
+    if (status.get('filtered') || status.getIn(['reblog', 'filtered'])) {
+      const minHandlers = this.props.muted ? {} : {
+        moveUp: this.handleHotkeyMoveUp,
+        moveDown: this.handleHotkeyMoveDown,
+      };
+
+      return (
+        <HotKeys handlers={minHandlers}>
+          <div className='status__wrapper status__wrapper--filtered focusable' tabIndex='0'>
+            <FormattedMessage id='status.filtered' defaultMessage='Filtered' />
+          </div>
+        </HotKeys>
+      );
+    }
+
     if (featured) {
       prepend = (
         <div className='status__prepend'>