[Feature Request] Support for getDisplayValue()

[vgtle]

Currently the raw value is returned from the scanner. While this is suitable for some cases, when using different formats, it get difficult to extract the actual value from the code returned from this library as this is different for each format. Beside the getRawValue() (See Documentation), it also possible to use getDisplayValue(). As this package tries to be simple and hide any complex configuration, switching to getDisplayValue() or adding an option to also return the getDisplayValue(): qrCodeCallback: (rawCode, displayCode) { ... }, could be a good option to not worry about the underlaying scanner format. I already implement this feature for myself (See Fork) and i hope that a good option can be found to support this.

[vgtle]

If providing both options in the qrCodeCallback is a valid option, I would not mind to implement this and provide a PR for this