Move GitLab Operator project out of `gl-openshift` group

Let's consider moving the GitLab Operator project out of the gl-opensfhift group into a non-OpenShift-specific group.

For example: gitlab-org/gitlab-operator

While we're on the topic, this reminds me of a discussion that @WarheadsSE mentioned regarding a group named something similar to cloud-native, which could house the Operator as well as CNG, Charts, etc.