This patch updates the sync code to include the
`RequestedRequiredStates` type.
This patch also adds `RoomInfo::handle_encryption_state` which
is able to mark an encryption state as synced depending of
`RequestedRequiredStates` (read the comment in the code).
This patch also updates the documentation of
`RoomInfo::handle_state_event` to clarify the impact of a
`m.room.encryption` state event.
Ivan Enderlin
31e0bfa400