Group runners should also run forks
Description
A fork (username/project) of an upstream project (group/project) can not be build with the "group" runner. Of course the forks are not part of the group but it would be way more easier to register it once and build also the forks. Now we have to register specific runners and add them manually to all the projects and forks.
Proposal
Add an option which can be enabled to also run forks when register a group runner.