Introduce a StartChatFlowCoordinator instead of handing a navigation stack to the Screen Coordinator. (#4674)

* Introduce a basic StartChatFlowCoordinator.

* Move the rest of the start chat flow from the screen coordinator into the flow coordinator.

* Add a UI test for the entire start chat flow.

* Refactor CreateRoom… to CreateRoomScreen…

ElementX/Sources/UITests/UITestsScreenIdentifier.swift

@@ -22,8 +22,6 @@ enum UITestsScreenIdentifier: String {
     case multipleProvidersAuthenticationFlow
     case bugReport
     case createPoll
-    case createRoom
-    case createRoomNoUsers
     case encryptionSettings
     case encryptionSettingsOutOfSync
     case encryptionReset
@@ -44,8 +42,7 @@ enum UITestsScreenIdentifier: String {
     case roomWithUndisclosedPolls
     case serverSelection
     case sessionVerification
-    case startChat
-    case startChatWithSearchResults
+    case startChatFlow
     case userSessionScreen
     case userSessionScreenReply
     case userSessionSpacesFlow