Add a Python version of arnied varlink interface

Add a Python version of arnied varlink interface

Also add as many typings as possible.

Can be easily used from within an IBS VM that has the varlink module
installed:

```
    from pyi2ncommon.arnied_api import Arnied, GetCnfQuery
    cnfs = Arnied.get_cnf(GetCnfQuery("USER"))
    user = cnfs.vars[0]

    assert user.name == "USER"
    assert user.instance == 1
    assert user.data == "admin"
```