Backport a few virt PRs (saltstack#272)

* Fix virt update when cpu and memory are changed

If CPU is changed, the memory change would be short circuited. This is a
regression introduced by PR saltstack#58332

* virt: add VM memory tunning support

* avoid comparing string with integer

* fix pre-commit failure

* Properly fix memory setting regression in virt.update

The 'mem' property in the virt.update value should indicate the result
of a live memory setting. The value should be an int in KiB. Fixing the
code and tests for this.

* virt: add stop_on_reboot parameter in guest states and definition

It can be needed to force a VM to stop instead of rebooting. A typical
example of this is when creating a VM using a install CDROM ISO or when
using an autoinstallation profile. Forcing a shutdown allows libvirt to
pick up another XML definition for the new start to remove the
firstboot-only options.

* virt: expose live parameter in virt.defined state

Allow updating the definition of a VM without touching the live
instance. This can be helpful since live update may change the device
names in the guest.

Co-authored-by: firefly <guoqing_li@pm.me>
Co-authored-by: gqlo <escita@pm.me>

changelog/57639.added

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+Memory Tuning Support which allows much greater control of memory allocation

changelog/58589.added

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+Allow handling special first boot definition on virtual machine