Expose pragmatic models through pypi's vrp_cli package

[reinterpretcat]

At the moment (1.22.0), the package exposes only minimal set of functions needed to run the solver:

https://github.com/reinterpretcat/vrp/blob/v1.22.0/vrp-cli/src/lib.rs#L412-L418

Here, all data is passed as a raw serialized string. Ideally, we need to support strictly typed way to run the solver. Pyo3 and maturin provides some ways to do it and this needs to be investigated. Challenges:

• no pyo3 dependency in pragmatic
• avoid duplication