8.0 migration of account_banking_payment

Summary of commits here:
* move account_banking_payment out of unported
* split it in two modules: account_banking_payment_transfer, and account_banking_payment_term
* drop the part of account_banking_payment that was dealing with bank statements
* use workflow triggers to move the payment orders to done when the transfer moves are reconcile
* migrate and improve the payment roundtrip test suite
* fix a bug that was causing the transfer moves to be wrongly numbered