Enforce json schema for config.json

[guybartal]

As a user I want to know that I've configured my experiment correctly and know the possible values per setting
So the experiment will fail fast and not in the middle of a long run.

Tasks

Beta Give feedback

1. add jsonschema package
2. create json schema for all possible values for config.json
3. validate json schema and throw an error upon running any step
4. validate json schema upon pre-commit for sample and ci configuration

Technical Notes:

• https://www.linkedin.com/pulse/mastering-json-schema-validation-python-developers-guide-singh-ebffc/