[pve-devel] add qemu guest agent command support

[Alexandre Derumier]

This patch series add code to send command to quest guest agent.

The procotol is qmp, so I have reuse as much as possible the current qmpclient


the only big difference is that we can't pass an id to a request, so we must send a guest-sync command with an id before the real command


command
--------
{ "execute": "guest-sync", "arguments": { "id": 123456 } }{"execute":"guest-ping"}

result
------------
{ "return": 123456}\n{"return": {}}