Load scope definitions dynamically

Related to https://gitlab.developers.cam.ac.uk/uis/devops/api/gateway-ops/-/issues/75 on the Gateway, we would like a more automated way to describe scopes. As part of https://gitlab.developers.cam.ac.uk/uis/devops/api/gateway-ops/-/issues/75 we will probably end up with a mechanism to specify supported scopes alongside a product which we should design in a way which allows re-use by this application.