Implement contract for fetching a single NFT

[rynoV]

Frontend needs this for the individual item pages

Plan:

• Use Ogmios' utxo query to get the utxo at the TxIn for the current item page
  • Will likely need to update CTL to support this query type
• Make sure this utxo is actually unspent
  • Not sure if ogmios will return a spent tx output, have to check
• If the utxo has been spent, requery the script address to find the updated utxo for the current item page
  • Probably update a local cache too
• Return the NFT data

[rynoV]

Not sure if ogmios will return a spent tx output, have to check

Checked, doesn't look like it, it will error. Makes sense since the query is for a Utxo

[rynoV]

If the utxo has been spent, requery the script address to find the updated utxo for the current item page

This seems like it would be better suited to the frontend. The contract should probably be minimal and just indicate in its return type if the txo has been spent