Goal

• When upgrading a non-RHEL system to RHEL, to be able to install Red Hat-signed packages we need to import the Red Hat GPG key.
• Also, on a successfully converted&upgrades system there shouldn't be the CentOS Stream GPG key installed anymore for security.

Acceptance criteria

• leapp-repository rpm bundles the RPM-GPG-KEY-redhat-release 
• a leapp actor imports the RPM-GPG-KEY-redhat-release
• a leapp actor removes the CentOS Stream GPG key
• GPG key-related report messages are checked whether they are correct