Add theming support, and support for other top level configuration to swiftui views with VectorHostingViewController, VectorContentModifier. Add VisibilityModifier. Move from List to VStack.

Riot/Modules/Common/SwiftUI/VectorContentView.swift

@@ -0,0 +1,39 @@
+// 
+// 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 SwiftUI
+
+/**
+ A Modifier to be called from the topmost SwiftUI view before being added to a HostViewController
+ Provides any app level configuration the SwiftUI hierarchy might need(E.g. to monitor theme changes).
+ */
+@available(iOS 14.0, *)
+struct VectorContentModifier: ViewModifier {
+    
+    @StateObject var themeObservor = ThemeObserver.shared
+    
+    func body(content: Content) -> some View {
+        content
+            .theme(themeObservor.theme)
+    }
+}
+
+@available(iOS 14.0, *)
+extension View {
+  func vectorContent() -> some View {
+    self.modifier(VectorContentModifier())
+  }
+}