[IMP] move account.move.line.get_balance() to account_banking_payment_export
[IMP] move 'structured' reference type to account_banking_payment_export
[MIG] move account_banking_payment out of __unported__and rename to account_banking_payment_transfer
[IMP] split account_banking_payment from account_banking

We drop the bank statement related part and we manage
the state of payment order with workflow transitions
triggered by the reconciliation of moves lines on the
transfer account.
[IMP] do not attempt to create transfer moves for payment lines without associated ar/ap move line

Otherwise, it is not possible to execute such payment order if the
payment mode has a transfer account. And I can't see how it could
make sense if the transfer move cannot be reconciled in the first place.
[IMP] workflow triggers when unreconciling move lines too

As the workflows listening on account_move_line are triggered upon
reconciliation, it makes sens to trigger them upon unreconcile too.
[MIG] migrate payment test suite
[IMP] upgrade payment roundtrip test suite

Support native v8 bank statement reconcile and
extend it to test the reconciliation state of transfer moves.
[IMP] move the payment term filter to a standalone module account_payment_mod_term