add WorkoutStateManager for ViewModel functionality

WorkoutsPlus/Configuration/Defaults.swift

@@ -15,7 +15,6 @@ public class Defaults: ObservableObject {
 		// TODO: isOnboarding should be true before shipping
 		@AppStorage("isOnboarding") public var isOnboarding = false
 		@AppStorage("isTrainerMode") public var isTrainerMode = false
-		@AppStorage("isWorkingOut") public var isWorkingOut = false
 		
 		@AppStorage("userId") public var userId = UUID().uuidString
 		@AppStorage("defaultWorkoutId") public var defaultWorkoutId: String = ""

WorkoutsPlus/Configuration/NavigationManager.swift

@@ -14,6 +14,20 @@ class NavigationManager: ObservableObject {
 				path = NavigationPath()
 				path.append(destination)
 		}
+		
+		func popToRoot() {
+				path = NavigationPath()
+		}
+		
+		func pop() {
+				if !path.isEmpty {
+						path.removeLast()
+				}
+		}
+		
+		func push(_ destination: NavigationDestination) {
+				path.append(destination)
+		}
 }
 
 enum NavigationDestination: Hashable {