Description of problem:
Expose disk serial number via virtctl

Version-Release number of selected component (if applicable):

1. virtctl version
   Client Version: "v0.53.1"
   Server Version: "v0.49.0-155-g32b905704"

How reproducible:
100%

Steps to Reproduce:
1. prepare a VM with the following definition

disks:

• bootOrder: 1
  disk:
  bus: scsi
  name: rootdisk
  serial: WD-WMAP9A966149

2. start the guest

3. check the guest xml

1. oc rsh virt-launcher-asb-vm-dv-ocs-cephrbd-rpjts virsh dumpxml 1
   ...
   <disk type='block' device='disk'>
   <driver name='qemu' type='raw' cache='none' error_policy='stop' io='native'/>
   <source dev='/dev/rootdisk' index='1'/>
   <backingStore/>
   <target dev='sda' bus='scsi'/>
   <serial>WD-WMAP9A966149</serial>
   <boot order='1'/>
   <alias name='ua-rootdisk'/>
   <address type='drive' controller='0' bus='0' target='0' unit='0'/>
   </disk>
   ...

4. check the disk info via virtctl

1. virtctl guestosinfo asb-vm-dv-ocs-cephrbd
   ...
   "fsInfo":
   Unknown macro: { "disks"}

   ,
   ...

Actual results:
The serial number of disk is not reported

Expected results:
The disk name could change, e.g. if the disk bus changed, then disk name changed. but the serial number would not change. It is better to report the serial number.
It may help management application find matching disk.

Additional info: