Add script for executing a command against a given list of VMs associated with self host runners

As per internal discussion, this script would be useful for usage on the runner hosts, for detecting issues with the GitHub runner baselines.

No files, tests, or entry points are named in the issue. First clarify how the VM list and self-hosted runner association are represented, which command interface and host environment are expected, and what baseline checks define success; done means a documented script can execute the requested command across the specified VMs.

Written by the indexing model from the issue text.