implement PVE Version addition for QEMU machine

implement PVE Version addition for QEMU machine

With our QEMU 4.1.1 package we can pass a additional internal version
to QEMU's machine, it will be split out there and ignored, but
returned on a QMP 'query-machines' call.

This allows us to use it for increasing the granularity with which we
can roll-out HW layout changes/additions for VMs. Until now we
required a machine version bump, happening normally every major
release of QEMU, with seldom, for us irrelevant, exceptions.
This often delays rolling out a feature, which would break
live-migration, by several months. That can now be avoided, the new
"pve-version" component of the machine can be bumped at will, and
thus we are much more flexible.

That versions orders after the ($major, $minor) version components
from an stable release - it can thus also be reset on the next
release.

The implementation extends the qemu-machine REGEX, remembers
"pve-version" when doing a "query-machines" and integrates support
into the min_version and extract_version helpers.

We start out with a version of 1.

Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>
Reviewed-by: Stefan Reiter <s.reiter@proxmox.com>