Oculus backend: refactor the use of GLSurfaceView

[liaxim]

Per VrApi.h

The API does not work with an Android Activity using a GLSurfaceView. The GLSurfaceView
class manages the window surface and EGLSurface and the implementation of GLSurfaceView
may unbind the EGLSurface before onPause() gets called. As such, there is no way to
leave VR mode before the EGLSurface disappears. Another problem with GLSurfaceView is
that it creates the EGLContext using eglChooseConfig(). The Android EGL code pushes in
multisample flags in eglChooseConfig() if the user has selected the "force 4x MSAA" option
in settings. Using a multisampled front buffer is completely wasted for time warp
rendering.

Alternatively an Android NativeActivity can be used to avoid manually handling all
the life cycle events. However, it is important to select the EGLConfig manually
without using eglChooseConfig() to make sure the front buffer is not multisampled.