Execute script before
we need to execute some hooks before a VM is started for the first time (i.e. after a VM is created or an existing VM is respawned with delete-recreate). Currently, we use a custom hook with state=PENDING for this. Unfortunately, the hook script is executed asynchronously and the VM may be assigned and start to boot while the hook scripts are still running. Therefore, occasionally the VM startup fails because not all hooks have been executed in time. Therefore, it would be great to have the possibility to request that a hook script must have completed before the VMs lifecycle continues.