Description of problem:

{ 'execute': 'query-command-line-options', 'arguments': { 'option': 'drive' } }

{
    "return": [
       	{
            "parameters": [
            ],
            "option": "drive"
        }
    ]
}


Currently we have three QemuOptsList (qemu_common_drive_opts,
qemu_legacy_drive_opts, and qemu_drive_opts)

only qemu_drive_opts is added to vm_config_groups[]

We query commandline options by checking information in vm_config_groups[],
so we can only get a NULL parameter list now.

Another issue is we also can't query legacy options of -drive.

Libvirt is relying on the query-command-line-options for deciding whether to support drive discard options.