vmm: Add id option to VFIO hotplug

Add a new id option to the VFIO hotplug command so that it matches the
VFIO coldplug semantic.

This is done by refactoring the existing code for VFIO hotplug, where
VmAddDeviceData structure is replaced by DeviceConfig. This structure is
the one used whenever a VFIO device is coldplugged, which is why it
makes sense to reuse it for the hotplug codepath.

Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>

tests/integration.rs

@@ -2409,7 +2409,7 @@ mod tests {
                  -i \
                  -X PUT http://localhost/api/v1/vm.add-device \
                  -H 'Accept: application/json' -H 'Content-Type: application/json' \
-                 -d '{\"path\":\"/sys/bus/pci/devices/0000:00:07.0\"}'",
+                 -d '{\"path\":\"/sys/bus/pci/devices/0000:00:07.0\",\"id\":\"vfio123\"}'",
             )?;
             thread::sleep(std::time::Duration::new(10, 0));
 
@@ -2444,15 +2444,13 @@ mod tests {
             // Let's now verify that we can correctly remove the virtio-net
             // device through the "remove-device" command responsible for
             // unplugging VFIO devices.
-            // "vfio2" is used here because the two previous devices will be
-            // affected with the values "vfio0" and "vfio1" by default.
             guest.ssh_command_l1(
                 "sudo curl \
                  --unix-socket /tmp/ch_api.sock \
                  -i \
                  -X PUT http://localhost/api/v1/vm.remove-device \
                  -H 'Accept: application/json' -H 'Content-Type: application/json' \
-                 -d '{\"id\":\"vfio2\"}'",
+                 -d '{\"id\":\"vfio123\"}'",
             )?;
             thread::sleep(std::time::Duration::new(10, 0));