Add support for CD-ROMs / ISOs

[nirvdrum]

A common approach to creating a new VM is to mount an ISO from a datastore and mark it as connected at power on. There's a few places where direct support for this would be handy. E.g., if VirtualMachine had utility method a la disks for CD-ROMs.

[cdickmann]

Sounds good. I don't have much time to work on this, but would be happy to merge a pull request

[skpy]

We solved this same problem by explicitly adding the VirtualCdrom device info in the new VM hash.

What we're struggling with now is programmatically detaching these VirtualCdrom devices after the machine has booted. Our attempts so far all result in the guest crashing hard. 😢