Add the Use Case selection screen to the onboarding flow.

RiotSwiftUI/Modules/Onboarding/UseCase/MockOnboardingUseCaseScreenState.swift

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+// 
+// 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
+import SwiftUI
+
+/// Using an enum for the screen allows you define the different state cases with
+/// the relevant associated data for each case.
+@available(iOS 14.0, *)
+enum MockOnboardingUseCaseScreenState: MockScreenState, CaseIterable {
+    // A case for each state you want to represent
+    // with specific, minimal associated data that will allow you
+    // mock that screen.
+    case `default`
+    
+    /// The associated screen
+    var screenType: Any.Type {
+        OnboardingUseCase.self
+    }
+    
+    /// A list of screen state definitions
+    static var allCases: [MockOnboardingUseCaseScreenState] {
+        // Each of the presence statuses
+        [.default]
+    }
+    
+    /// Generate the view struct for the screen state.
+    var screenView: ([Any], AnyView)  {
+        let viewModel = OnboardingUseCaseViewModel()
+        
+        // can simulate service and viewModel actions here if needs be.
+        
+        return (
+            [self, viewModel],
+            AnyView(OnboardingUseCase(viewModel: viewModel.context)
+                .addDependency(MockAvatarService.example))
+        )
+    }
+}