[Systemroles] Central management of system roles repos

[Richard Megginson]

https://github.com/linux-system-roles/.github/pull/7

This allows the system roles maintainers to much more easily roll out fixes
and updates to github actions, linter configurations, etc.  Saves time and
ensures consistency among all of the roles, while at the same time allowing
per-role customization.

Coming soon - github repo settings management, such as branch protection
rules (which are now *wildly* inconsistent among all of our repos).