Update to Jackson 2.4.3

- Update pom to 2.4.3 from 2.4.2
- Enable the CBOR data header (aka tag) from the CBOR Generator to provide binary identification like the Smile format
- Check for the CBOR header and ensure that the data sent in represents a "major type" that is an object
- Cleans up `JsonVsCborTests` unused imports

Closes #7640
Maybe you should also check that third and fourth are different from -1, otherwise this indicator of a missing byte (-1) is going to be converted to a legal byte (255) via the cast?