Fixes #978 - Message forwarding support

* Add support for message forwarding

* Move the TimelineProvider within the RoomProxy to avoid it going out of sync and have it automatically register for timeline updates on init

* Implement single selection form button style for message forwarding

* Add searching and filter out the source room from the list

* Fixed emoji screen initial search bar height

* Add view models tests

* Add changelog

* Update strings

* Tweaks following code review

ElementX/Sources/Screens/MessageForwardingScreen/MessageForwardingScreenModels.swift

@@ -0,0 +1,54 @@
+//
+// Copyright 2022 New Vector Ltd
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+import Foundation
+
+enum MessageForwardingScreenViewModelAction {
+    case dismiss
+    case send(roomID: String)
+}
+
+struct MessageForwardingScreenViewState: BindableState {
+    var rooms: [MessageForwardingRoom] = []
+    var selectedRoomID: String?
+    
+    var visibleRooms: [MessageForwardingRoom] {
+        if bindings.searchQuery.isEmpty {
+            return rooms
+        }
+        
+        return rooms.filter { $0.name.localizedStandardContains(bindings.searchQuery) }
+    }
+    
+    var bindings = MessageForwardingScreenViewStateBindings()
+}
+
+struct MessageForwardingScreenViewStateBindings {
+    var searchQuery = ""
+}
+
+enum MessageForwardingScreenViewAction {
+    case cancel
+    case send
+    case selectRoom(roomID: String)
+}
+
+struct MessageForwardingRoom: Identifiable, Equatable {
+    let id: String
+    let name: String
+    let alias: String?
+    let avatarURL: URL?
+}