Notes: improvements in draksetup modify-vm0

[psrok1]

Small todolist of improvements because I'm too lazy to make a separate tickets for:

• modify-vm0 begin Check if there is only vm-0 running before beginning modify-vm0: it should be safe to run with vm-n but active other VMs are locking storage, so we may have a bad surprise during commit
• modify-vm0 commit Handle reprofile errors: vm-0 is already saved, vm-1 in spinned up but something went wrong during reprofiling and user don't know what to do
• modify-vm0 commit Handle initial snapshot errors: automatic rollback or let user do the rollback?
• modify-vm0 commit Allow to commit without reprofile (when I just know that my change was minor and I don't have any changes in Windows files)