Tip credit support in Check API

The Check API now provides an earning type called `tip_credit_adjustment_to_minimum_wage` to allow you to enter in wages for tip credit workflows properly. Tip credit payroll items can be entered into the Check API using this new earning type and the accompanying `tip_credit_amount` field. Note that `cash_tip` and `paycheck_tip` should be used in conjunction with this earning type if an employee's cash_wage is below the state's typical minimum wage.

Learn more about Tip Credits here.