[FEATURE] Add custom weights for RRF in hybrid search

[ryanbogan]

What solution would you like?

Currently, RRF in hybrid search does not support the ability to add custom weights in the search pipeline to modify the reciprocal rank fusion algorithm. We should add this functionality to give the user more control over the score-based ranking algorithm.

Requirements:

1. Add custom weight array input to the search pipeline request
2. Incorporate these weights into the rank score calculations