Error when multiple transactions submitted

[tomjeatt]

See: https://discord.com/channels/745259537707040778/1156899801800130621

This can most easily be replicated on lending by submitting a transaction and then immediately submitting another one. The cause of the issue is understood and related to the nonce. This has been mitigated on the parachain by keeping track of how many transactions an account has signed and predicting the next nonce to be used.

A similar mitigation will be needed in the UI.

Note: this is a medium priority because the problem resolves itself after a few seconds, so resubmitting the transaction normally succeeds. This was reported by Sander (and is easily replicated), but it's not been reported by anyone in the community so it's likely that submitting multiple transactions so close together is an edge case.