Trace transaction replies in txSubmissionOutbound after transactions are sent

[intricate]

I noticed that in #1688 I was mistakenly tracing TraceTxSubmissionOutboundSendMsgReplyTxs events before the transactions had been successfully sent.

[mrBliss]

I see. Tracing afterwards makes sense, but I'm not sure it's worth making the code that much more complex (I mean adding the @m@ to SendMsgReplyTxs). What do you think @dcoutts?

[mrBliss]

This requires a comment (here or near L195) saying that tracing itself will be executed after sending the reply.

[intricate]

I see. Tracing afterwards makes sense, but I'm not sure it's worth making the code that much more complex...

@mrBliss: Do you feel the same way about the approach in the first commit?

data ClientStTxs txid tx m a where
  SendMsgReplyTxs   :: [tx]
                    -> ([tx] -> m ())
                    -> ClientStIdle txid tx m a
                    -> ClientStTxs  txid tx m a