isValidDeviceEngagementString
Validates the supplied string is a valid QR code based on device engagement structure (as per section 8.2.2.3 of ISO 18013-5).
This function will:
Check the supplied string is prefixed with
mdoc:
.Decode the trailing portion of the string as Base64 into a CBOR structure and validate it against the expected data structure as per the CDDL of section 8.2.2.3 in ISO/IEC 18013-5:2021.
Return
Boolean indicating whether the provided string is a valid device engagement structure.