Fix OnMapReady delivery when a new style is requested before the map is initialized

[LukasPaczos]

Fixes a small regression introduced by the #13133 - when requesting a new style before the drawing surface is initialized, before, we were relying on NativeMapView being created after the view hierarchy is established, which means, that calls like mapView#setStyleUrl done in the #onCreate would add the style to the MapboxMapOptions, because NativeMapView was still null. Now, we are initializing the NativeMapView immediately, which means that calling mapView#setStyleUrl would start loading the style instantly introducing a race condition - we would either create the drawing surface before the style is loaded, then the execution continued as expected, or the style would've loaded first, resulting in not delivering OnMapReady at all.

The other part of this PR removes the usage of the deprecated OnMapChange listener across the project.