sam local generate step functions mocking configuration

### Describe your idea/feature/enhancement

With the recent announcement of "Mocked Service Integrations" for Step Functions, it would be great to have a new command (something like `sam local generate-step-functions-mock` to generate the `MockConfigFile.json` with SAM, just like we can generate events using `sam local generate-event`.

### Proposal

Based on the step function state machine configuration, it would be great to have a wizard that asks for each state (service integration) what the mocking configuration should be. At the end of the process, it generates the `MockConfigFile.json`

### Additional Details