Room screen header (#86)

* #35 Create `ElementNavigationController` subclass

* #35 Add encryption icons

* #35 Add avatar and encryption badge image to the room screen view model

* #35 Create `RoomHeaderView` class

* #35 Replace room title with a RoomHeaderView instance in the toolbar

* #35 Add changelog

* #35 Introduce `UITestScreenIdentifier` and refactor ui tests

* #35 Fix old tests

* #35 add some tests for room screen

* #35 Use svgs instead of pngs

* #35 Fix PR remarks

ElementX/Sources/Screens/RoomScreen/RoomScreenModels.swift

@@ -15,6 +15,7 @@
 //
 
 import Foundation
+import UIKit
 
 enum RoomScreenViewModelAction {
 
@@ -35,6 +36,8 @@ enum RoomScreenViewAction {
 
 struct RoomScreenViewState: BindableState {
     var roomTitle: String = ""
+    var roomAvatar: UIImage?
+    var roomEncryptionBadge: UIImage?
     var items: [RoomTimelineViewProvider] = []
     var isBackPaginating = false
     var bindings: RoomScreenViewStateBindings