Add trade duration to completed screen

[HenrikJannsen]

It would be useful to see how much time the trade took.

Here a discussion about the conceptual and technical aspects of that.

One option is to use the button click to complete the trade as the completion time stamp. But that might add delay if the user has not been that active. The trade can be seen as completed after the BTC payment tx got confirmed. Even here, its questionable if the confirmation time is the best metric or to use the moment when seen in the network, as with low miner fees there might be considerable delay.
One of those options would work for on-chain settlement but not for LN.
For LN we have a confirm step at the buyer but that is not enforced. The seller can complete his side after sending the BTC via LN without waiting for the manual confirmation of the buyer.

As all relevant protocol state changes are reflected by log messages and those have a date time stamp we could utilize those for the completion date (only the click on completion is not reflected by a log message, but even that could be added if we want to cover that event by utilizing log messages.

Currently there is no meta data in the log message for the trade state which triggered the sending of it. We could add such a field to the BisqEasyOpenTradeMessage (requires care for backward compatibility).

From all the options I think the utilization of log messages might be the most flexible and useful. Having the trade state in the log message might also help for future use cases, like if we add a trade history but want to delete peer private data like bank account we could easier do that by deleting that log messages which can be filtered by the trade state.

To summarize my suggestion:

• Add trade state field to BisqEasyOpenTradeMessagein a backward compatibility way
• Send a log message once user clicks the Complete trade button.
• For trade duration display use the time when user has clicked the Complete trade button. Explain with a info icon tooltip how that duration is calculated and include also the the other relevant duration (tx in mempool, tx confirmed and for LN: LN payment sent, LN payment confirmed by buyer if present)
• Maybe, add a list of all log messages to the trade details.