Fix "method_complexity" issue in src/eventSourcing/esAggregateRoot.ts

[svallory]

Function APPLY_CHANGE has a Cognitive Complexity of 15 (exceeds 5 allowed). Consider refactoring.

https://codeclimate.com/github/cashfarm/plow/src/eventSourcing/esAggregateRoot.ts#issue_5acf071bc2c4490001000048