[ENHANCEMENT] Re-weighting the search results by field

[jn2clark]

Is your feature request related to a problem? Please describe.
Currently the tensor searches are executed concurrently over individual fields (https://github.com/marqo-ai/marqo/blob/mainline/src/marqo/tensor_search/tensor_search.py#L951) and the output is sorted according to their scores.
It would be good to have the ability to -re-weight particular fields upon returning by multiplying the scores from a particular field by a scalar (https://github.com/marqo-ai/marqo/blob/mainline/src/marqo/tensor_search/tensor_search.py#L1051-L1064).

Describe the solution you'd like
Something in the search endpoint to provide a weighting to the fields being searched over.
For example (python client), client.index(index_name).search(query, searchable_attributes=[('col1', 0.5), 'col2', 'col3'])

Describe alternatives you've considered
Nothing

[jn2clark]

completed #300