Concurrency Fixes (#283)

* Review places where MainActor used

* Adapt to MainActor changes, avoid redundant task detachments

* Move Rust client operations into a dedicated concurrent queue, make init async

* Add changelog

* Fixed small working for awaiting non-async method

* Remove some redundant tasks

* Put back some main actors

* Fix tests

* Fixed timeline updates when the number of items doesn't change. Keeps more previous home screen room data between reloads

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

ElementX/Sources/Services/Timeline/RoomTimelineProvider.swift

@@ -45,11 +45,11 @@ class RoomTimelineProvider: RoomTimelineProviderProtocol {
     init(roomProxy: RoomProxyProtocol) {
         self.roomProxy = roomProxy
         itemProxies = []
-        
+
         Task {
             let roomTimelineListener = RoomTimelineListener()
             await roomProxy.addTimelineListener(listener: roomTimelineListener)
-            
+
             roomTimelineListener
                 .itemsUpdatePublisher
                 .collect(.byTime(DispatchQueue.global(qos: .background), 0.5))