COLO: Add a new RunState RUN_STATE_COLO

COLO: Add a new RunState RUN_STATE_COLO

Guest will enter this state when paused to save/restore VM state
under COLO checkpoint.

Cc: Eric Blake <[email protected]>
Cc: Markus Armbruster <[email protected]>
Signed-off-by: zhanghailiang <[email protected]>
Signed-off-by: Li Zhijian <[email protected]>
Signed-off-by: Gonglei <[email protected]>
Reviewed-by: Dr. David Alan Gilbert <[email protected]>
Reviewed-by: Eric Blake <[email protected]>
Reviewed-by: Amit Shah <[email protected]>
Signed-off-by: Amit Shah <[email protected]>