feat: custom tx fee on direct-send

[theborakompanioni]

Since JoinMarket-Org/joinmarket-clientserver#1597 it is possible to specify the txfee directly on direct-send operations.

Note: This feature must be hidden behind a version flag as it will only be available with backend version >= 0.9.11.

As a user, I want to specify a custom tx fee when creating a single transaction, so I not have to edit the config values on a per transaction basis. This can be done by adding a custom tx input field, prefilled with the config value, to the send options on non-collaborative sends.

Later, this functionality can be used when creating/unlocking/renewing fidelity bonds (#678).

[kristapsk]

From Jam UX perspective, if custom fee can be specified for direct-send, wouldn't you like to have it also for /wallet/{walletname}/taker/coinjoin? Implementation should not be hard, scripts/sendpayment.py already support it for both coinjoin and non-coinjoin sends.

[theborakompanioni]

From Jam UX perspective, if custom fee can be specified for direct-send, wouldn't you like to have it also for /wallet/{walletname}/taker/coinjoin? Implementation should not be hard, scripts/sendpayment.py already support it for both coinjoin and non-coinjoin sends.

That would indeed be awesome. 🚀
Thanks @kristapsk