* Add FilterRetriever draft
* Implement FilterRetriever and add tests
* Update comparison to compare whole docs instead of just contents
* Expose FilterRetriever at the retrievers level
* Update docstring (add example usage)
* Add filter_retriever in the API reference docs config
Update retriever search path to start one dir level higher
* simplify _documents_equal
* improve usage example
---------
Co-authored-by: anakin87 <stefanofiorucci@gmail.com>
* fix!: `InMemoryBM25Retriever` no longer returns documents that have a score of 0.0
Also update tests to accommodate the new behavior.
* Remove superfluous code