This refactor is in support of SAML token authentication: #63209
Avoid use of govmomi.Client as it only supports username+password authentication via SessionManager.Login().
Using vim25.Client directly will allow VCP to add other authentication methods,
such as SessionManager.LoginByToken().
- vsphere.conf (cloud-config) is now needed only on master node
- VCP uses OS hostname and not vSphere inventory name
- VCP is now resilient to VM inventory name change and VM migration
If node does not exist, node's volumes will be detached
automatically and become available. So mark them detached and
return false without error.
Fix#50266
