x/auth: add sign-batch command (cosmos#6350)

The command processes list of transactions from file
(one StdTx each line), generate signed transactions
or signatures and print their JSON encoding, delimited
by '\n'. As the signatures are generated, the command
increments the sequence number automatically.

Author: @jgimeno
Reviewed-by: @alessio

cmd/simcli/main.go

@@ -132,6 +132,7 @@ func txCmd(cdc *codec.Codec) *cobra.Command {
 		bankcmd.NewSendTxCmd(clientCtx),
 		flags.LineBreak,
 		authcmd.GetSignCommand(cdc),
+		authcmd.GetSignBatchCommand(cdc),
 		authcmd.GetMultiSignCommand(cdc),
 		authcmd.GetValidateSignaturesCommand(cdc),
 		flags.LineBreak,