Gap: Add tx_index Field to Asset Transactions Response

[edridudi]

Hey Koios,
I found a minor gap between Koios and BF for the Asset Transaction Endpoint.
Please add the tx_index field for the Asset Transaction Model.

There can be a lot of transactions per one asset and querying tx info in a loop for each tx hash could cause a big load on Koios instances.
furthermore, I think it would be even better to add any other tx-related data to save in tx info queries as long as it is not too complex or not a significant weight on the system.

Thanks a lot!

[rdlrt]

Please add the tx_index field for the Asset Transaction Model.

asset_utxos added in PR #227 (alongwith aligning schema for account_utxos, address_utxos, credential_utxos, utxo_info, script_utxos)

You can test those at guild.koios.rest