RHEL PoC

[neersighted]

This is a PoC for building RHEL packages assuming that a RHEL username/password is available in the environment.

This is mostly intended for internal use by Docker, as it is assumed that the main utility is performing builds with a 'real RHEL' for enterprise customers. As such, there is currently no verification in this upstream repository.

However, when a unencumbered RHEL-equivalent distribution (e.g. Rocky) is supported, it will make sense to add verification for that distribution and generalize the 'rhel' infrastructure in this repo.