Use Consistent Method Naming in AbstractController

## Use Consistent Method Naming in AbstractController

### Acceptance Criteria
1. `AbstractController::getSimpleResponse` is called `createSimpleResponse` to match `createNotFoundResponse`.
1. `AbstractController::getJsonResponse` is called `createJsonResponse` to match `createNotFoundResponse`.
1. Anywhere those helper methods are used, they are renamed.

### Tasks
- None

### Additional Notes
- None