enh: enable reranking through Cross Encoding

[VarinThakur01]

This PR adds the feature of reranking results using Cross Encoding.
The following things have been added

• Allow passing a rerank_config inside the existing similarity search methods to support reranking.
• Introduce HanaReranker as a standalone reranker to rerank documents.
• Addition of test cases for above 2 additions
• Adding Reranking Documentation in the noteboook

PR Extensions (For future)

• Replace model validations from Dummy queries to System Views (Will be done together for VECTOR_EMBEDDING() and CROSS_ENCODE())
• Currently, similarity_search_with_relevance_scores() function doesn't support reranking as it uses the implementation from the parent class. (As the relevance functions are not properly set, we will add the support of reranking in a future PR after fixing the relevance_score functions)

[yonarw]

Three smaller remarks left, otherwise good for merge.