Add derivative tally based k_eff search support for material perturbations #3690
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Description
This PR extends the recently added Model.keff_search method for material input parameters by leveraging derivative tallies. It adds least-squares curve fitting over a combination of K_eff evaluations and its derivatives as an alternative method to GRSecant's curve fitting. We have observed considerable reduction in the required number of MC evaluations for some cases which is consistent with the primary work by @smharper as reported here: https://dspace.mit.edu/bitstream/handle/1721.1/106690/969775837-MIT.pdf
It is an initial work on #980 and is related to: #3569, #2693.
Checklist