customers would like to call python code from within a workflow definition

Acceptance criteria:

Provide 2 examples of workflows using python to the orhcestrator-demo repository:

1. An example that uses python function
2. An example that uses python program that is delivered as part of the project

Both examples should provide steps on how to run it locally (for development) and on the cluster (production).

Custom dockerfile will have to be provided for the second example

For local development, we have to check if that can be supported using the 'kn-workflow run' or should there be changes to support the use of devmode image for running the workflow locally.