[Glitch] Add CSS class to replies

Port 2bbec9f4da to glitch-soc

app/javascript/flavours/glitch/components/status.js

@@ -475,6 +475,7 @@ export default class Status extends ImmutablePureComponent {
     const computedClass = classNames('status', `status-${status.get('visibility')}`, {
       collapsed: isCollapsed,
       'has-background': isCollapsed && background,
+      'status__wrapper-reply': !!status.get('in_reply_to_id'),
       muted,
     }, 'focusable');