Extend forEachIndex to work with internal HasFields objects like Cell, Row, etc

As a follow-on to #3147 which added support for iterating over the fields in a JSON object, extend forEachIndex to iterate over any internal OpenRefine object which implements the HasFields interface.

Proposed solution

Extend forEachIndex to work with Row, Cell, Record, Recon, ReconCandidate, WrappedRow, WrappedCell, CellTuple.

Alternatives considered

It may be desirable to also/instead add a way to get the field names directly using something like row.fieldNames() or row.keys()

Additional context

This can be used as a memory aid for field names in the following fashion:

forEachIndex(row,k,v,k) => ['flagged', 'starred', 'cells', 'record']