add options object to mockEventCreator methods

[Jbarget]

creating an issue for:
https://github.com/dwyl/aws-lambda-test-utils/blob/master/mockEvent.js#L5-L12

Ability to pass options object to:

• createDynamoDBEvent 9e4b7a4
• createSNSEvent
• createS3Event
• createAPIGatewayEvent

[Jbarget]

@nelsonic can you assign me?
I'll start with the createDynamoDBEvent method and get your feedback

[Jbarget]

@nelsonic can you add me as a collaborator? trying to push a branch but getting 403 :)