Move specs for project and group resolver to a shared spec
https://gitlab.com/gitlab-org/gitlab/blob/master/spec/graphql/resolvers/project_resolver_spec.rb and https://gitlab.com/gitlab-org/gitlab/blob/master/spec/graphql/resolvers/group_resolver_spec.rb are almost 100% copy-paste. This might be a good opportunity to move their tests to shared spec to make sure we're testing it consistently