add get_top_k_cosine_similarity method to get max top k score and index

[hwaking]

Row-wise cosine similarity between two equal-width matrices and return the max top_k score and index, the score all greater than threshold_score. @vowelparrot @dev2049 @hwchase17

it's useful when we want to get the top k score and index after similarity compute. just like the following example:

input example

x = [[1, 2, 3, 4], [1, 2, 2, 2]]
y = [[1, 2, 3, 5], [1, 2, 9, 5], [2, 2, 3, 5]]
index_score_list = get_top_k_cosine_similarity(x, y, top_k=2, threshold_score=0.94)
print('index_score_list：', index_score_list)

output result

index_score_list： [[(0, 0.9939990885479664), (2, 0.9860132971832692)], [(2, 0.9415130835240085)]]