[FEATURE] Implement Migration Control Totals

[GregorSchroeder]

Is your feature request related to a problem? Please describe.
The previous Cohort Component Model allowed users to specify total in/out migration control totals for each increment as the model moved from the base/launch year to the horizon year such that users could explore different migration scenarios.

Describe the solution you'd like
A simple solution would be an input file (csv/JSON/etc....) of increments with either both in-migration and out-migration totals or simply a net migration total. This would also require a check to ensure the input file follows a required structure and contains all necessary increment years.