* minor migration refactor
* overwrite usdx claims with latest reward indexes
* add missing usdx claims in migration
* add script to calculate missing usdx rewards
* generate missing rewards using preliminary data
* add missing usdx rewards in migration
* update missing rewards data to use correct genesis
* test rewards were not decreased
* add tests for missing reward calculations
* clarify function names
* test to assert total new rewards are as expected
* remove unecessary todo item
