SwiftUI NavigationController and UserNotificationControllers (#309)

* Fixes #286 - Adopted the new SwiftUI NavigationStack based NavigationController throughout the application
* Fixes #315 - Implemented new user notification components on top of SwiftUI and the new navigation flows
* Add home screen fade animation between skeletons and real rooms
* Bump the danger-swift version used on the CI and swiftlint with it
* Renamed Splash to Onboarding, Empty to Splash

UnitTests/Sources/OnboardingViewModelTests.swift

@@ -0,0 +1,23 @@
+//
+// 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 XCTest
+
+@testable import ElementX
+
+class OnboardingViewModelTests: XCTestCase {
+    // Nothing to test, the view model has no mutable state.
+}