Add fine-grained filtering options in python fetch_traces API to match web UI

[evangriffiths]

Describe the feature or potential improvement

Specifically I'd like to be able to fetch traces with where the session_id contains a particular string. This is possible in the web UI

But in the python sdk, the session id has to be an exact match: https://langfuse.com/docs/sdk/python/low-level-sdk#traces

Additional information

No response