singlethreaded and multithreaded upsert implementation for pinecone h…

[StankoKuveljic]

• add pinecone index wrapper for single threaded and multithreaded upsert
• add integration tests
• modified notebook example

BREAKING CHANGE:

• instead off passing the pinecone.Index to the retriever PineconeHybridSearchRetriever it expects the wrapper instance PineconeIndexUpsert that can be get from PineconeIndexUpsert.get_index(index_name='index-name', pool_threads=1).

Alternatively, we can pass the flag to add_texts method should this be threaded or not and use appropriate upsert method, but in that case the client-code needs to worry about if they instantiated pinecone.Index with thread pool or not to use this method properly.

NOTE:

• Do NOT Merge