Support for redeemers that contain indices

[euonymos]

@nau pointed out that many protocols use indices stored in the redeemers as part of an optimization effort. If the editing function supports them, it might be of great help. Now, the editor treats redeemers as opaque data, but nothing prevents us from having:

newtype IndexRedeemer = ...

-- Extracts all indices as they appear in the Data
extractIndiced :: IndexRedeemer -> [Int]

-- Update indices
updateIndices :: IndexRedeemer -> [Int] -> IndexRedeemer

The editor will need to keep track of objects that a particular redeemer references.
The plain redeemers should be preserved for regular cases when direct indexing is not used.