Description of problem:

UpdateVmDiskCommand should be refactored to use the CoCo infrastructure.
The amend, extend and update disk will be executed serially, if an
operation will fail the process will be stopped.

Currently several properties will not be able to be updated in the same operation like extend and amend.
With CoCo those should be updated properly.

The relevant operation that will be reflected is the REST operation:
  http://localhost:8080/ovirt-engine/api/vms/111/diskattachments/222

With the following body:
  <disk_attachment>
      <disk>
         ...
      </disk>
  </disk_attachment>

Version-Release number of selected component (if applicable):
4.1.2

Steps to Reproduce:
1. Update Vm's disk
2.
3.