Use `permissions` (project and group) for `RemoteRepository.admin`
Use `permissions` (project and group) for `RemoteRepository.admin`

When syncing `RemoteRepository` in GitLab we were only checking if the user was
the owner of the project, but we weren't checking for permissions given by
belonging to a group.

This commit makes usage of 40 (maintainer) and 50 (owner) permission levels to
check these permissions granted by being part of a group.

rtfd/readthedocs.org,rtfd/readthedocs.org,rtfd/readthedocs.org,rtfd/readthedocs.org