Rework WebosSurfaceManagerRemoteClient to handle different message types

Signed-off-by: Simon Busch <morphis@gravedo.de>
Implement method to send message to restore a buffer after rendering

Signed-off-by: Simon Busch <morphis@gravedo.de>
Remove unneeded increment of buffer reference count

Signed-off-by: Simon Busch <morphis@gravedo.de>
Move buffer allocation into own class

Signed-off-by: Simon Busch <morphis@gravedo.de>
Track buffer handle ownership to free either the handle or the actual memory

Signed-off-by: Simon Busch <morphis@gravedo.de>