Add script to help store self-hosted runner creds in AWS SSM

We can't create self-hosted runners "on-demand", so we need to
pre-create a "pool" of them for use by the auto-scaled nodes.

This script automated the process of converting the short-lived token in
to long-lived credentials (by using the runner binaries in a temporary
directory) and then storing the resulting files in AWS's ParameterStore
8 files changed