Feat: Enable crb with dnf module

[jokokucing]

For EL images (centos, RHEL, ROCKY, ALMA) to enable the EPEL repo crb is required,

Would be nice to have a crb install option

`dnf config-manager --set-enabled crb"

[xynydev]

CRB seems to be a repository.

Tasks

• Decide on schema for enabling repository. repos.crb: boolean could work
• Implement enabling/disabling with a simple if/else in the code
• Update TypeSpec and documentation, making sure to outline which base OS this is meant for
• Submit PR for review