Initial setup ready for PIN/Biometric app lock. (#1876)

* Add AppLockCoordinator and WindowManager.

UnitTests/Sources/AppLockScreenViewModelTests.swift

@@ -0,0 +1,46 @@
+//
+// 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
+
+@MainActor
+class AppLockScreenViewModelTests: XCTestCase {
+    var appLockService: AppLockService!
+    var viewModel: AppLockScreenViewModelProtocol!
+    
+    var context: AppLockScreenViewModelType.Context { viewModel.context }
+    
+    override func setUp() {
+        AppSettings.reset()
+        appLockService = AppLockService(keychainController: KeychainControllerMock(), appSettings: AppSettings())
+        viewModel = AppLockScreenViewModel(appLockService: appLockService)
+    }
+    
+    func testUnlock() async throws {
+        // Given a valid PIN code.
+        let pinCode = "0000"
+        
+        // When entering it on the lock screen.
+        let deferred = deferFulfillment(viewModel.actions) { $0 == .appUnlocked }
+        context.send(viewAction: .submitPINCode(pinCode))
+        let result = try await deferred.fulfill()
+        
+        // The app should become unlocked.
+        XCTAssertEqual(result, .appUnlocked)
+    }
+}