Use weak reference from SessionInfo

[wyfo]

Describe the feature

SessionInfo<'static> use a strong reference to Session. This is can be an issue because it may prevents the session to be closed by not being able to claim ownership of the Arc.

In normal languages with scoped variables, this is not really an issue, but in esoteric script dialects like Python, this is a real issue, see this example of the reworked api:

with zenoh.open(conf) as session:
    info = session.info
    print(f"zid: {info.zid()}")

The context manager exit method (closing the session) will fail, because the ownership of the session cannot be claimed – yes, even with context manager.
del info statement must be explicitly added to make it work. With weak reference into SessionInfo, that would not be an issue.

[wyfo]

I've changed the Python API to use a weak reference to session instead of simply wrapping the rust type, so this is not a problem anymore.
Thank you @OlivierHecart for the idea.