RecordsRequestHandler::check*Access signatures change

The first argument to the check*Access template methods may now be null to indicate testing for access to create a new record. Any RecordsRequestHandler descendants overriding any of these methods will need their signature updated upon pulling down emergence-skeleton v1.3.0+. Any custom access-checking logic should treat a null value for $Record as they would a phantom record. This relieves the need for consumers testing whether the current user can create a record to generate a phantom record just to pass for testing access.