Add source of localconfig (exposed routes) to the response of the response of the globalconfig endpoint #84

it would be helpful (e.g. for the federator) to have the path of the routing localconfig of each EIDA datacenter. (which is, obviously, an indication of the information source of this service, as well as an information with its own value (e.g., throughout EIDA, the only place to find lists of virtual networks).
Also, this information could resolve ambiguity of authoritativeness, if a data center e.g. has a static routing.xml exposed as well as the routing service itself with its ./localconfig endpoint.

As the FDSN data center json schema [https://github.com/FDSN/datacenter-registry/blob/master/FDSN-datacenter-registry-1.0.schema.json] does not allow for additional attributes of either the datacenter or the archive entities, I would suggest to describe the localconfig as a service of its own type (name: "eidaws-routing-localconfig").