RPM Support

Pulp filters out errata without packages during publish.
So between remote source and publish result there can be difference in the number of errata.
These errata will never be shown as applicable, it's informative in case someone reads it.

Example of text-only errata:
- when container image is released
- when packages getting deprecated in that repo are announced

These errata don't have any RPM packages associated with them.

Current behaviour is not a bug and such errata are filtered out on purpose.
When implementing this RFE, make sure to distinguish between an erratum which has never had packages in its pkglist and an erratum which doesn't have packages because they are not present in a repo.