Allow for distinct endpoints for services in orchestrator configurations

Current situation

The orchestrator object in the opentfconfig file only allows to specify a custom port for a service:

orchestrators:
- orchestrator:
    server: http://foo.example.com
    ports:
      observer: 1234
      receptionist: 5678
  name: foo

Desired outcome

A way to specify additional custom data per service, such as a path prefix.

orchestrators:
- orchestrator:
    server: http://foo.example.com
    services:
      observer:
        port: 1234
        prefix: observer
      receptionist:
        port: 5678
  name: foo

In the above example, the base endpoint for the observer service would be http://foo.example.com:1234/observer and the base endpoint for the receptionist service would be http://foo.example.com:5678.

An additional item could be added per service too, force-base-url, to overcome mis-configured reverse proxy installations.