Create a reducer to go back `Home` when finished sending

This is done as a seperate commit to demonstrate composing routing
logic where a 'child' feature can send messages to a 'parent'.

secant/Features/Home/Views/HomeView.swift

@@ -52,7 +52,10 @@ struct HomeView: View {
                                 transaction: .demo,
                                 route: nil
                             ),
-                            reducer: .default.debug(),
+                            reducer: SendReducer.default(
+                                whenDone: { viewStore.send(.updateRoute(nil)) }
+                            )
+                            .debug(),
                             environment: ()
                         )
                     )

secant/Features/Send/SendStore.swift

@@ -28,6 +28,17 @@ extension SendReducer {
             return .none
         }
     }
+
+    static func `default`(whenDone: @escaping () -> Void) -> SendReducer {
+        SendReducer { state, action, _ in
+            switch action {
+            case let .updateRoute(route) where route == .showApprove(route: .showSent(route: .done)):
+                return Effect.fireAndForget(whenDone)
+            default:
+                return Self.default.run(&state, action, ())
+            }
+        }
+    }
 }
 
 // Mark: - SendStore