Add CollectionViewRightAlignFlowLayout to have right alignement display for collection view.

Riot/Modules/Common/CollectionView/CollectionViewRightAlignFlowLayout.swift

@@ -0,0 +1,29 @@
+// 
+// Copyright 2021 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 UIKit
+
+/// UICollectionViewFlowLayout with right align behavior
+class CollectionViewRightAlignFlowLayout: UICollectionViewFlowLayout {
+
+    override var flipsHorizontallyInOppositeLayoutDirection: Bool {
+        return true
+    }
+
+    override var developmentLayoutDirection: UIUserInterfaceLayoutDirection {
+        return UIUserInterfaceLayoutDirection.rightToLeft
+    }    
+}