Changes

Refactor MSC params and add Wentzel VI params and data (#1129)

* Add Wentzel VI data

- Move common MSC data into separate structs
- Import geom_factor
- Check imported Wentzel VI data in test

* Add Wentzel VI params and MSC params interface

* Move common MSC params to physics

* Add helper class for constructing MSC params and address other feedback

* Remove geometry factor (currently unused)

* Fix test for float

* Change fact --> factor

* Add min/max energy methods to XsCalculator