Keys and scripts needed for producing a final transaction with a dummy signature.
                           Used for fee estimation during coin selection.
     {
       "pubkeys": [        (json array, optional, default=[]) Public keys involved in this transaction.
         "pubkey",         (string) A public key
         ...
       ],
       "scripts": [        (json array, optional, default=[]) Scripts involved in this transaction.
         "script",         (string) A script
         ...
       ],
     