Implement RBF via nonce arg

[zone117x]

Implement support for passing a nonce arg which can be used for performing a replace-by-fee.

[zone117x]

This arg is already supported:
--nonce=nonce Optionally specify a nonce for this transaction

The task here could be improving the command doc / readme to explain how this can be used for performing a replace-by-fee.

@MarvinJanssen do you have any insight into what might be helpful here for the entities who are using this util?

[MarvinJanssen]

Most entities that use this tool regularly have it integrated into their application flow. I should investigate which of them have a resolution mechanism for nonce issues / RBF built into their platform.