Remove public currentCameraPositionState property #500

Compose 4.3.0

#262 introduced a public currentCameraPositionState property. I don't think this was a good idea from an architectural standpoint, as this allows & suggests configuring the map from inside the map subcomposition by user code. Map configuration is generally intended to be done at the top level via parameters of the GoogleMap() composable. CameraPositionState is one of the parameters passed to GoogleMap(), duplicating responsibilities for CameraPositionState configuration.

If user code does need access to CameraPositionState from inside the subcomposition it can pass it down itself in whatever form it deems most appropriate: read-only position, read/write state, or some other kind of wrapper; captured lambda variable, parameter, or CompositionLocal. These decisions need to be left to user code.