Migration from MapboxNavigationProvider to MapboxNavigationApp

[kmadsen]

Resolves #128

Some initial ideas

I migrated ShowAlternativeRoutesActivity to the non-experimental apis to get a feel for how the migration will go. I think we should define some extensions because there is a lot of boilerplate.

If we defined MapboxNavigationApp extensions inside the core sdk, that could make it nicer. So I added an idea to the ShowCurrentLocationActivity example. This way your init function looks something like this? Just an idea.

    init {
        MapboxNavigationApp.setup(
            NavigationOptions.Builder(this)
                .accessToken(getString(R.string.mapbox_access_token))
                .build()
        ).attach(this)

        MapboxNavigationApp.attach(
            this,
            onResume = { registerLocationObserver(locationObserver) },
            onPause = { unregisterLocationObserver(locationObserver) },
        )
    }

[Zayankovsky]

I also noticed that both of the migrated examples are crashing because of trying to access application context in activity constructor.

[kmadsen]

I also noticed that both of the migrated examples are crashing because of trying to access application context in activity constructor.

Oh right, meant to use NavigationOptionsProvider so that the context is available by the time it is called

[kmadsen]

Another example for setting up something like MapboxNavigationApp

https://github.com/mapbox/mapbox-maps-android/tree/main/extension-androidauto#example-session-and-mapscreen

The MapboxCarApp uses a similar "registerObserver"/"unregisterObserver" pattern