Add ToJSON/FromJSON instances for EraTxAuxData
* Add ToJSON/FromJSON and NFData as EraTxAuxData superclass constraints * Add ToJSON/FromJSON for Metadatum * Add ToJSON/FromJSON for Data era and PlutusBinary * Add FromJSON for PoolCert, ConwayGovCert, DijkstraDelegCert, DijkstraTxCert era * Add ToJSON/FromJSON for ShelleyTxAuxData, AllegraTxAuxData, AlonzoTxAuxData * Add round-trip JSON property test for TxAuxData era