Payment on account events

Payment on account lifecycle and balance allocation.

Event type	Description	Identifiers
paymentOnAccount.created	A payment on account record was created	paymentOnAccountId
paymentOnAccount.allocated	A payment on account balance was allocated to an invoice (for example "Pay from account")	paymentOnAccountId
paymentOnAccount.unallocated	Unallocated balance was restored on a payment on account (for example after a refund against an invoice payment that used account funds)	paymentOnAccountId
paymentOnAccount.deleted	A payment on account record was deleted	paymentOnAccountId