Confirm button to prompt for ledger creation when no ledger selected

Originally brought up as feedback to the advanced/simple ledger mode task.

In simple mode:
Instead of disabling the confirm order button, can we
A. Leave it enabled
B. Popup a message that says "this customer doesn't have an account in Xero. Create one now? Yes/No
C. If the user says yes, then open the standard Xero (or other) account creation window, create the account, set it on division and allow confirm order...