merge, finish swiftui and add theming

Riot/Modules/Room/NotificationSettings/SwiftUI/FormSectionHeader.swift

@@ -0,0 +1,44 @@
+// 
+// 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
+
+@available(iOS 13.0, *)
+struct FormSectionHeader: View {
+    
+    @Environment(\.theme) var theme: Theme
+    var text: String
+    
+    var body: some View {
+        Text(text)
+            .foregroundColor(Color(theme.textSecondaryColor))
+            .padding(.top)
+            .font(Font(theme.fonts.footnote))
+    }
+}
+
+@available(iOS 13.0, *)
+struct FormSectionHeader_Previews: PreviewProvider {
+    static var previews: some View {
+        List {
+            SwiftUI.Section(header: FormSectionHeader(text: "Section Header")) {
+                Text("Item 1")
+                Text("Item 2")
+                Text("Item 3")
+            }
+        }.listStyle(GroupedListStyle())
+    }
+}