Allow FpPrint data to be extended on enrollment.

Allow FpPrint data to be extended on enrollment.

• Allow FPI_PRINT_NBIS to be extended rather than overridden if a user supplies an existing FpPrint template with data;
• Prints will only be extended if a device has the required feature. For image-based devices this feature is added by default since they typically do not have storage (this can be overridden at the child class level).

Extending an existing FpPrint requires passing a template print with existing data during the enrollment process. This is done because the caller is responsible for maintaining the fingerprint database and doing the necessary deserialization operations if needed. The existing example program is updated to show how to do that.