Ability to setup a VM startup/shutdown order in the cluster

It'd be nice to have a VM startup/shutdown order in the cluster. That allows to do staged cluster startup/shutdown.

Imagine we have 3 VM with `node1` having order of 10 and other 2 VMs having order of 100. Then `node1` should be started first and the other nodes should be started after the 1st one in parallel. Shutdown sequence should happen in a reversed order.

Start by locating the Puppet Bolt VM startup and shutdown entry points in the repository and tracing how cluster operations are sequenced. Define how numeric orders group parallel starts, reverse for shutdown, and handle the example with node1 at 10 and the other VMs at 100; done means staged startup and reversed shutdown work consistently.

Written by the indexing model from the issue text.