JOE can configure Agent URLs with prefix

Current Situation
with JS-1467 (or by using a reverse Proxy) it is possible to configure a process class for an Agent with a prefix inside the URL, e.g.

<process_class  max_processes="20" remote_scheduler="https://somehost:24445/test/agent_1"/>

• JOE has 2 fields for entering this URL
  • Host
  • Port
• It is not possible to use these to fields to configure the above process class

Desired Behaviour

• JOE should enable users to configure URLs with scheme, host, port and a custom prefix.
• this can be solved by removing the separate host and port fields in JOE and just providing one "Remote Scheduler" field.