[NXCM-5392] USe a specific content class for P2 composite group which is compatible with P2 content group
[NXCM-5392] Filtering repositories that can be grouped should look for formats compatible with format of group not the other way around
[NXCM-5392] Reverse content class compatibility check
[NXCM-5392] Compatibility can only be checked in one direction