Implement proper testing of module code

[OndrejHome]

Goal:

• avoiding stupid mistakes like syntax errors or unsupported syntaxes that are not detected by python -m py_compile library/*.py

Possible options:

1. full unit testing simulating the environment with cluster - https://docs.ansible.com/ansible/latest/dev_guide/testing_units_modules.html

• quite heave to implement all tests and will get stuck with outputs from given version of pcs, but works without special infrastructure

2. setting up infrastructure to test the roles with interactive use - have some roles and infrastructure with VMs that will actively use the modules and check for errors during execution of playbooks

• needs infrastructure to basically create clusters and run playbooks on them, will cover future changes in pcs, but needs infrastructure