Implement integration test between python and Rust

[gtema]

We need to ensure that the python Keystone and rust one can work together:

• token issued by python is accepted (with the same meaning) in Rust
• token issued by Rust accepted by python
• existing token validation returns same results for python and rust keystone

Idea is to start a 2 keystones in parallel in a workflow and start comparing them. "integration" workflow is the place where this functionality should be added