* Avoid reactivity bugs in how we track external state
Many of our hooks which attempt to bridge external state from an EventEmitter or EventTarget into React had subtle bugs which could cause them to fail to react to certain updates. The conditions necessary for triggering these bugs are explained by the tests that I've included.
In the majority of cases, I don't think we were triggering these bugs in practice. They could've become problems if we refactored our components in certain ways. The one concrete case I'm aware of in which we actually triggered such a bug was the race condition with the useRoomEncryptionSystem shared secret logic (addressed by a1110af6d5).
But, particularly with all the weird reactivity issues we're debugging this week, I think we need to eliminate the possibility that any of the bugs in these hooks are the cause of our current headaches.
* Reuse useTypedEventEmitterState in useLocalStorage
* Fix type error
This upgrade came with a number of new lints that needed to be fixed across the code base. Primarily: explicit return types on functions, and explicit visibility modifiers on class members.
