Add a Link New Device screen (behind a feature flag). (#4811)

ElementX/Sources/Screens/LinkNewDeviceScreen/LinkNewDeviceScreenCoordinator.swift

@@ -0,0 +1,55 @@
+//
+// Copyright 2025 Element Creations Ltd.
+//
+// SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial.
+// Please see LICENSE files in the repository root for full details.
+//
+
+import Combine
+import SwiftUI
+
+enum LinkNewDeviceScreenCoordinatorAction {
+    case linkMobileDevice
+    case linkDesktopComputer
+    case dismiss
+}
+
+struct LinkNewDeviceScreenCoordinatorParameters {
+    let clientProxy: ClientProxyProtocol
+}
+
+final class LinkNewDeviceScreenCoordinator: CoordinatorProtocol {
+    private let viewModel: LinkNewDeviceScreenViewModelProtocol
+    
+    private var cancellables = Set<AnyCancellable>()
+ 
+    private let actionsSubject: PassthroughSubject<LinkNewDeviceScreenCoordinatorAction, Never> = .init()
+    var actionsPublisher: AnyPublisher<LinkNewDeviceScreenCoordinatorAction, Never> {
+        actionsSubject.eraseToAnyPublisher()
+    }
+    
+    init(parameters: LinkNewDeviceScreenCoordinatorParameters) {
+        viewModel = LinkNewDeviceScreenViewModel(clientProxy: parameters.clientProxy)
+    }
+    
+    func start() {
+        viewModel.actionsPublisher.sink { [weak self] action in
+            MXLog.info("Coordinator: received view model action: \(action)")
+            
+            guard let self else { return }
+            switch action {
+            case .linkMobileDevice:
+                actionsSubject.send(.linkMobileDevice)
+            case .linkDesktopComputer:
+                actionsSubject.send(.linkDesktopComputer)
+            case .dismiss:
+                actionsSubject.send(.dismiss)
+            }
+        }
+        .store(in: &cancellables)
+    }
+        
+    func toPresentable() -> AnyView {
+        AnyView(LinkNewDeviceScreen(context: viewModel.context))
+    }
+}