The core of this is in the MarkedExecution class, with the remainder of the commit ensuring that the right marks and triggers are in place to do the firing.
Because everything is async/await and run through the RoomListStore, we don't have to worry about self-fed updates in the algorithm classes. This also means we have to trigger pretty much all the time.
Changes to tag ordering / list sorting get hit through two paths, so we mark before we do a bulk update and otherwise assume the call is coming in from outside.
