Egress controlled routing to external geo-replicated endpoints

[evanlouie]

As an operator, if my cluster consumes a service from a georeplicated external source, my cluster should be able to ping a single egress controlled endpoint within my cluster which will automatically route the request to the nearest working endpoint.

• The egress endpoint should periodically do liveness probes to the available endpoints.
• The egress endpoint should be able to accept configurations for ordered/weighted usage of the available external endpoints.