Introduce RHEL family

[mauromorales]

• merges the files for rockylinux and almalinux into a rhel dockerfile
• decided not to add fedora into this since, it requires to add the epel packages, which might make fedora too close to rhel for our community users. But wonder what you think, is it a good/bad idea to try to also merge that one?

Clean up fedora dockerfile

• remove packages which are already installed by default "coreutils" and "curl"
• make it similar to the other dockerfiles for easier maintenance

[Itxaka]

decided not to add fedora into this since, it requires to add the epel packages, which might make fedora too close to rhel for our community users. But wonder what you think, is it a good/bad idea to try to also merge that one?

IMHO I would merge all of them. What packages come from the epel repos? Only the needed ones like zfs? I think merging them all under the same family would be ok as in the end they will have the minimal packages required for a base Kairos flavor, but they can expand it with whatever afterwards, so they can also drop the epel repos on their custom dockerfiles no?

[mauromorales]

@Itxaka ok, will give it a shot and maybe from then we can see how much they differ.

[mauromorales]

I tried doing a pure rhel but it's a lot more work :( lots of packages are not available, not sure if they are named differently or if I need to enable some repo