[core] Service discovery of OpenAPI services in workflows

Motivation

In order to call an external OpenAPI service it’s necessary to know its OpenAPI description file and connect through a known service URI. Often such services can be closely related to the workflow and can run in the same namespace. Through service discovery we can enable workflows to find and call a service without specifying details of that service.

Goal

Enable service discovery of OpenAPI services in workflows

Scenarios

As a developer, I want to loosely couple my workflow with OpenAPI services within the same namespace so that I can easily switch between different service implementations

Expected outcomes

Operation state can set a new URI which will discover and call the particular service by an identifier