Render state items in the timeline and as the last message on the home screen. (#473)

* State events in the timeline WIP
* Implement membership change strings.
* Add other state event types and use in RoomSummaryProvider.

Co-authored-by: Stefan Ceriu <stefanc@matrix.org>

ElementX/Sources/Services/Client/ClientProxyProtocol.swift

@@ -61,7 +61,7 @@ enum PushFormat {
 protocol ClientProxyProtocol: AnyObject, MediaProxyProtocol {
     var callbacks: PassthroughSubject<ClientProxyCallback, Never> { get }
     
-    var userIdentifier: String { get }
+    var userID: String { get }
 
     var isSoftLogout: Bool { get }