radv: implement image->image copies using compute shader

radv: implement image->image copies using compute shader

This is required for having a separate compute queue, we
probably can't use this on GFX queue due to DCC.

v2: Set coord_components = 2 for itoi texture fetch. (Bas)

Signed-off-by: Dave Airlie <airlied@redhat.com>
Reviewed-by: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl>