Expose platform bindings for new OfflineManager APIs

[chloekraw]

With mapbox/mapbox-gl-native#15899 and mapbox/mapbox-gl-native#15967, we optimized the offline region deletion and ambient cache clearing APIs in GL-Native.

Before, deleting an offline pack and clearing the ambient cache would automatically trigger the SQLite VACUUM operation (in mbgl's packDatabase()) to erase the resources from disk and free up space. This operation is computationally expensive and would block the main thread, sometimes also causing the app to hang or crash.

mapbox/mapbox-gl-native#15899 decouples VACUUM from those APIs and mapbox/mapbox-gl-native#15967 adds a new API, runPackDatabaseAutomatically(bool) , which allows the developer configure whether packDatabase() is run automatically with deleteRegion() and clearAmbientCache(). By default, the value is true, enabling this change to be backwards compatible.

cc/ @mapbox/maps-ios @1ec5 @pozdnyakov