MatrixRTC MembershipManger: remove redundant sendDelayedEventAction and expose status (#4747)
* Remove redundant sendDelayedEventAction
We do already have the state `hasMemberEvent` that allows to distinguish the two cases. No need to create two dedicated actions.
* fix missing return
* Make membership manager an event emitter to inform about status updates.
- deprecate isJoined (replaced by isActivated)
- move Interface types to types.ts
* add tests for status updates.
* lint
* test "reschedules delayed leave event" in case the delayed event gets canceled
* review
* fix types
* prettier
* fix legacy membership manager