[new feature] add (another model-free) data valuation method: complexity-gap score

[jwmueller]

Cleanlab's data valuation module: https://docs.cleanlab.ai/master/cleanlab/datalab/internal/issue_manager/data_valuation.html

Currently solely supports Data Shapely based on K-nearest-neighbor models.

Goal: add more efficient Data Valuation methods as options for this module.
One good one to consider (should benchmark against Cleanlab's current KNN Data Shapely) is the complexity-gap method published in this paper:

DATA VALUATION WITHOUT TRAINING OF A MODEL
https://arxiv.org/abs/2301.00930