Add RAG implementation using Gemini LLM and Embedding using BeyondLLM

[lucifertrj]

Beyond LLM helps build RAG experimentations and evaluations in just 5 lines of code.

This PR adds the example notebook, that implements Chat with your own PDF.

• Uses Gemini Embeddings as default
• Uses Gemini LLM as default
• Execute RAG Triad for the RAG evaluation

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[lucifertrj]

@MarkDaoust Any changes required?