virtio-pci: Introduce APIs to execute device parts admin commands

Introduce APIs to handle the execution of device parts admin commands.

These APIs cover functionalities such as mode setting, object creation
and destruction, and operations like parts get/set and metadata
retrieval.

These APIs will be utilized in upcoming patches within this series.

Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Yishai Hadas <yishaih@nvidia.com>
Link: https://lore.kernel.org/r/20241113115200.209269-5-yishaih@nvidia.com


Signed-off-by: Alex Williamson <alex.williamson@redhat.com>