Finish extraction

- Moves SwiftUI code out of Riot and into RiotSwiftUI which has no dependency on Matrix SDK.
- Git wasn't smart enough to see the file moves. Most feature function has remain unchanged. 1 change I did make was remove NotificationSettingsViewModel's dependence on MxPushRule, so that the view model could be moved into RiotSwiftUI.
- Add LocaleProvider to abstract VectorL10n's use of Matrix SDK language so it can be used in RiotSwiftUI.
- Split Theme into UKit/SwiftUI version to remove RiotSwiftUI's dependence on ThemeService and ThemeV1.
- Migrated from ThemeObserver to ThemePublisher. We push updates to ThemePublisher so that we can remove ThemeService as dependency.
- Add .DS_Store to .gitignore

RiotSwiftUI/Modules/Common/DependencyInjection/DependencyContainer.swift

@@ -0,0 +1,48 @@
+// 
+// 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 Foundation
+
+/**
+ Used for storing and resolving dependencies at runtime.
+ */
+struct DependencyContainer {
+    
+    // Stores the dependencies with type information removed.
+    private var dependencyStore: [String: Any] = [:]
+    
+    /**
+     Resolve a dependency by type.
+     Given a particlar `Type` (Inferred from return type),
+     generate a key and retrieve from storage.
+     */
+    func resolve<T>() -> T {
+        let key = String(describing: T.self)
+        guard let t = dependencyStore[key] as? T else {
+            fatalError("No provider registered for type \(T.self)")
+        }
+        return t
+    }
+    
+    /**
+     Register a dependency.
+     Given a dependency, generate a key from it's `Type` and save in storage.
+     */
+    mutating func register<T>(dependency: T) {
+        let key = String(describing: T.self)
+        dependencyStore[key] = dependency
+    }
+}