Fix room search updating unread count (Vue left-menu)

Fix room search updating unread count (Vue left-menu)

Use roomId's in search results that point back to the roomMap. So whenever we update information for a room via the updateRoom action, the new information flows

Fix https://gitlab.com/gitlab-org/gitter/webapp/issues/2189

Testing strategy

1. Add the feature toggle, node ./scripts/utils/feature-toggle.js --name vue-left-menu --description "Left menu using Vue (alpha)"
2. Enable the feature toggle
   • Enable: http://localhost:5000/api_web/features/vue-left-menu/1
   • Disable: http://localhost:5000/api_web/features/vue-left-menu/0
3. Have a room with some unread messages and notice the green unread badge
4. Search for the room with unread messages
5. Click on the room
6. Notice the messages get marked as read and the room in left-menu search results updates to no unreads