[Feature request]: Expose NavigationApi.setNotificationOptions() in google_navigation_flutter to allow custom PendingIntent and notification content

Currently, when using google_navigation_flutter, the Android SDK automatically shows a system navigation notification while guidance is active.

This notification:

is green and comes from the Navigation SDK,

contains no customization options in Flutter,

and tapping it does not bring the app from background to foreground.

On the native Android Navigation SDK, there is an API:

NavigationApi.setNotificationOptions(NotificationOptions options);

where developers can provide a NotificationContentProvider and a custom PendingIntent.
This allows us to handle notification tap events (for example, to bring the app back to foreground).

Unfortunately, this API is not exposed in google_navigation_flutter. As a result:

We cannot replace the default notification.

We cannot control what happens when the user taps it.

We cannot provide a consistent UX across Android and iOS.

Request

Please expose NavigationApi.setNotificationOptions() (and related NotificationOptions + NotificationContentProvider) through google_navigation_flutter, so that Flutter apps can:

Customize the navigation notification content.

Provide a PendingIntent that resumes the Flutter app from background when the notification is tapped.

Ensure parity with the native Android SDK.

Why this is important

Without this, the default navigation notification is confusing for users: tapping it does nothing.

On iOS, there is no such notification, so the UX is inconsistent.

Apps often need to bring the user back into the app when navigation is tapped (e.g. to show trip details or active guidance screen).

✅ This request is essentially to bridge an existing Android SDK feature into Flutter, not a new feature request.