Requirements for handling event types used for E2EE
There are four event types specifically relevant for E2EE:
All info regarding each event type can be found here: https://matrix.org/docs/guides/e2e_implementation.html
Generally it seems that all event types should be forwarded to the module. To support them it is to figure out, what else we'll need aside from the pure events themselves.
#4 (closed) is required for further work on