hw/vfio/ap: store object indicating AP config changed in a queue

hw/vfio/ap: store object indicating AP config changed in a queue

Creates an object indicating that an AP configuration change event
has been received and stores it in a queue. These objects will later
be used to store event information for an AP configuration change
when the CHSC instruction is intercepted.

Signed-off-by: Rorie Reyes <rreyes@linux.ibm.com>
Reviewed-by: Anthony Krowiak <akrowiak@linux.ibm.com>
Link: https://lore.kernel.org/qemu-devel/20250609164418.17585-3-rreyes@linux.ibm.com
Signed-off-by: Cédric Le Goater <clg@redhat.com>