feat(datasets): Added the Experimental LangfuseTraceDataset

[SajidAlamQB]

Description

Related to: #1203

This PR adds LangfuseTraceDataset as an experimental dataset to enable Langfuse integration for tracing in Kedro pipelines. The implementation for this dataset can be found here: kedro-org/kedro-academy#77.

The dataset provides three modes of integration:

langchain: Returns CallbackHandler for LangChain tracing
openai: Returns wrapped OpenAI client with automatic tracing
sdk: Returns raw Langfuse client for manual instrumentation

Development notes

• Added LangfuseTraceDataset to kedro_datasets_experimental.langfuse module
• The dataset manages Langfuse credentials and sets required environment variables during initialisation
• Implements read-only pattern as tracing clients are not data to be persisted
• Added documentation
• Updated RELEASE.md

Checklist

• Opened this PR as a 'Draft Pull Request' if it is work-in-progress
• Updated the documentation to reflect the code changes
• Updated jsonschema/kedro-catalog-X.XX.json if necessary
• Added a description of this change in the relevant RELEASE.md file
• Added tests to cover my changes
• Received approvals from at least half of the TSC (required for adding a new, non-experimental dataset)

[ElenaKhaustova]

It looks great!

Left two suggestions to double check.

[ElenaKhaustova]

👍

[ravi-kumar-pilla]

Hi @SajidAlamQB , Overall it looks good. I left few minor comments. Other than that it LGTM. Thank you