[Feature] Support for Set mapping in the evaluation schema

[Udayraj123]

The evaluation schema has introduced a new key conditionalSets to handle conditional marking schemes and answer keys based on a matcher.

• This will be useful to support different test paper sets based a common position of the test code/booklet code/set code field
• The format string should have access to all fields read from the image, and also the filepath (and optionally filename)
• In future when custom fields like Barcode are supported, we can use the same schema to map each barcode/QR code to a different evaluation schema within a single evaluation.json file