Allow changing the VNC password on an already created VM

[brodriguez-opennebula]

Description
The VNC password for a VM created on a template that does not have any password cannot be added after it is running

Use case
This may be useful to secure VNC consoles that can be accessed from outside with no downtime or minimal

Interface Changes
A "Setup VNC password" option should appear in some dialog of the VM

Additional Context
The libvirt domain line for the VM should go from

 <graphics type='vnc' port='6305' autoport='no' listen='0.0.0.0'>

to

 <graphics type='vnc' port='6305' autoport='no' listen='0.0.0.0' passwd='new_pass'>

Progress Status

• Code committed
• Testing - QA
• Documentation (Release notes - resolved issues, compatibility, known issues)