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/Screens/RoomScreen/View/TimelineItemList.swift

@@ -152,6 +152,11 @@ struct TimelineItemList: View {
             // Otherwise just update the items
             timelineItems = context.viewState.items
         }
+        .onChange(of: context.viewState.items, perform: { items in
+            if timelineItems != items {
+                timelineItems = items
+            }
+        })
         .background(GeometryReader { geo in
             Color.clear.preference(key: ViewFramePreferenceKey.self, value: [geo.frame(in: .global)])
         })