[sonataflow] Implement a getting started example for operator use case

[domhanak]

Description

As a SonataFlow developer I want to have an example I can try and use with kn workflow plugin CLI tool.

Goal is to provide a simple example that will be usable with kn workflow plugin; showcases the capabilities of the CLI and user can:

• use run command to run it locally
• use deploy command to deploy it a cluster ( local or remote, does not matter, login is required )
• use gen-manifest to modify how it is deployed.

Implementation ideas

Idea is to implement simple example that will query an endpoint if an input is provided.