Add the option to get the cosine similarity value (score) for each returned label in the search function

[HasanYousef]

Hi,
it will be awesome if we get the value of the cosine similarity score to compare the returned values in the search function.

For example, if the search function got called with vector = x and k = 4 and returned [5, 2, 0, 3], currently we can't tell how similar vector 5 is to the query vector x compared to how similar vector 2 is to the query vector x.