GUAC-656: Add simple surface and stubs.
GUAC-656: Implement alloc/free for surface.
GUAC-656: Add instructions to stubs. Match prototype of surface function to that of protocol function.
GUAC-656: Migrate RDP to guac_common_surface.
GUAC-656: Send size and dispose when alloc/free surface.
GUAC-656: Free buffer last - surface needs to send dispose.
GUAC-656: Flush default surface after handling updates.
GUAC-656: Remove surface resize - not needed for now.
GUAC-656: Add logging message noting intent (actual surface not implemented).
GUAC-656: Implement flush. Implement draw.
GUAC-656: Implement rect, clean logic.
GUAC-656: Implement transfer and copy.