Implement AppLockScreen as per the designs. (#1925)

Fix a bug in the unlock flow

UnitTests/Sources/AppLock/AppLockScreenViewModelTests.swift

@@ -44,7 +44,8 @@ class AppLockScreenViewModelTests: XCTestCase {
         
         // When entering it on the lock screen.
         let deferred = deferFulfillment(viewModel.actions) { $0 == .appUnlocked }
-        context.send(viewAction: .submitPINCode(pinCode))
+        viewModel.context.pinCode = pinCode
+        context.send(viewAction: .submitPINCode)
         let result = try await deferred.fulfill()
         
         // The app should become unlocked.

UnitTests/__Snapshots__/PreviewTests/test_appLockScreen.1.png

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:6d8b859217f475cd3477e96e8f501662d7c288d731800112d97af0d8c7718273
+size 129515