Rename project.repository_files to project.rpm_repository_files

🔥 Problem

For the RPM Repository, we added support files that are linked to a project (and not a single package).

As such, this association was added to the Project model.

The problem is that the association was named repository_files. This is extremely confusing as a GitLab project is generally a git repository . Having an association named repository_files is not great at all.

🚒 Solution

Prefix the association name with rpm:

Rename project.repository_files to project.rpm_repository_files.