Add Simple Template Example

- Add a simple Template example that shows a user profile with avatar, displayName and presence.
- ScreenCoordinator: closure based with less protocols and delegates.
- Reducer: Reducer function that manages all state modifications.
- SwiftUI View: Decomposes UI into appropriate sub components.
- Uses Theme and Dependency Management Infrastructure

RiotSwiftUI/Modules/Template/SimpleProfileExample/ViewModel/TemplateUserProfileViewModel.swift

@@ -15,13 +15,15 @@
 //
 
 import SwiftUI
+import Combine
 
 @available(iOS 14.0, *)
 class TemplateUserProfileViewModel: ObservableObject {
     
     private let userService: TemplateUserServiceType
+    private var cancellables =  Set<AnyCancellable>()
     
-    @Published var viewState: TemplateUserProfileViewState
+    @Published private(set) var viewState: TemplateUserProfileViewState
     
     private static func defaultState(userService: TemplateUserServiceType) -> TemplateUserProfileViewState {
         return TemplateUserProfileViewState(avatar: userService.avatarData, displayName: userService.displayName)
@@ -30,5 +32,30 @@ class TemplateUserProfileViewModel: ObservableObject {
     init(userService: TemplateUserServiceType, initialState: TemplateUserProfileViewState? = nil) {
         self.userService = userService
         self.viewState = initialState ?? Self.defaultState(userService: userService)
+        
+        userService.presencePublisher
+            .map(TemplateProfileStateAction.updatePresence)
+            .receive(on: DispatchQueue.main)
+            .sink(receiveValue: self.dispatch(action:))
+            .store(in: &cancellables)
+    }
+    
+    /**
+     Send state actions to mutate the state.
+     */
+    private func dispatch(action: TemplateProfileStateAction) {
+        var newState = self.viewState
+        reducer(state: &newState, action: action)
+        self.viewState = newState
+    }
+    
+    /**
+     A redux style reducer, all modifications to state happen here. Recieves a state and a state action and produces a new state.
+     */
+    private func reducer(state: inout TemplateUserProfileViewState, action: TemplateProfileStateAction) {
+        switch action {
+        case .updatePresence(let presence):
+            state.presence = presence
+        }
     }
 }