Opens an account in the requested currency for an active client. The currency must be enabled for your
integration.The account is opened within this request, and the response contains its identifier. Payment credentials
(for example, an IBAN or an account number) are then issued asynchronously for each payment method available
for the currency. Each result is reported with a credentialsIssued or credentialsIssueFailed webhook; you
can also follow it with GET /baas/Accounts/{id}.externalId is your identifier of the account; a request with the externalId of an existing account is
rejected.Errors:
404 Not Found - the client does not exist or is not active yet;
409 Conflict - an account with this externalId already exists;
422 Unprocessable Content - an account cannot be opened in this currency.