* feat: normalize embeddings for cosine sim
* WIP add test case for faiss cosine
* input to faiss normalize needs to be an array of vectors
* fix: test should compare correct result embedding to original embedding
* add sanity check for cosine sim
* fix typo
* normalize cosine score
* Update docstring
Co-authored-by: Malte Pietsch <malte.pietsch@deepset.ai>