advertise endpoint "path" on the Service

[joel-bluedata]

We advertise "urlScheme" through the name of the relevant port object, but we don't advertise "path". The URL path can be quite useful for a GUI client composing clickable links.

Unfortunately there's no way to annotate an individual port object, and we probably shouldn't try to smuggle additional information through the port name. (BTW for more recent K8s versions, the port object now has an appProtocol field that we could use to advertise "urlScheme", although we would need to continue name-munging for now to maintain backward compat.)

So we'll have to annotate the Service. Potentially one annotation per port, unless we want to figure out an annotation value format that could be used to store a list of these per-port paths.