Returns brief information for transactions currently in the pool.
txs — array of tx_rpc_brief_info objects.
tx_rpc_brief_info object's fields:
fee — unsigned int; transaction fee.
id — string; hash identifier.
sz — unsigned int; size of serialized transaction in bytes (the same as blob_size in tx_rpc_extended_info).
total_amount — unsigned int; sum of all transaction outputs.