Use Coordinator and Non-ViewController Based Handling of Order Notifications

[shiki]

As a continuation of #2669, we should also upgrade our Order notifications to rely on a Coordinator instead of a ViewController. This is so we can avoid issues like #2254.

Currently, we use a static method to handle Order notifications:

woocommerce-ios/WooCommerce/Classes/ViewRelated/MainTabBarController.swift

Lines 315 to 331 in 046e2a8

	private static func presentNotificationDetails(for note: Note) {
	switch note.kind {
	case .storeOrder:
	switchToOrdersTab {
	guard let ordersVC: OrdersRootViewController = childViewController() else {
	return
	}
	ordersVC.presentDetails(for: note)
	}
	default:
	break
	}
	ServiceLocator.analytics.track(.notificationOpened, withProperties: [ "type": note.kind.rawValue,
	"already_read": note.read ])
	}

We should follow #2669 so that notification handling is:

• Handled by an Order-tab-specific Coordinator
• Does not rely on a valid OrdersViewController state.
• Reactive. Observes PushNotificationsManager.