Expose internal ability to retrieve rendering SurfaceControl

In order to coordinate what surfaces are being exposed on the screen, we
need access to the SurfaceControl in order to access its layerId. While
this works for systems such as ViewRootImpl, it is not available for
SurfaceView.

Flag: EXEMPT internal access
Bug: 404617897
Test: Build and unit test
Change-Id: I8a6e36a82640b7c65d3005d4449cc9d01cb705b9