vfio: Introduce new files for CPR definitions and declarations

vfio: Introduce new files for CPR definitions and declarations

Gather all CPR related declarations into "vfio-cpr.h" to reduce exposure
of VFIO internals in "hw/vfio/vfio-common.h". These were introduced in
commit d9fa4223b30a ("vfio: register container for cpr").

Order file list in meson.build while at it.

Cc: Steve Sistare <steven.sistare@oracle.com>
Reviewed-by: Steve Sistare <steven.sistare@oracle.com>
Link: https://lore.kernel.org/qemu-devel/20250326075122.1299361-22-clg@redhat.com
Signed-off-by: Cédric Le Goater <clg@redhat.com>