[Feature]: Dynamic RAM management.

[Kisel13]

Is your proposal related to a problem?

If the VM is not using RAM, it is still not available to the host.

Describe the solution you'd like.

Use dynamic memory ballooning and add options to set the minimum and maximum RAM amount.

Describe alternatives you've considered.

Change the parameters every time the VM needs more memory. And forget about the fact that the host doesn't have access to unused RAM allocated to the VM.

Additional context

No response