Create new VA

This API creates a new virtual account for a specified customer via a selected Payment Service Provider (PSP). It returns the details of the virtual account including the account number and related metadata. **Request Body:** | Field | Type | Required | Description | | --- | --- | --- | --- | | `pspId` | string | Yes | Identifier for the Payment Service Provider (e.g., `"finmo"`). | | `customerId` | string | Required for Finmo only. It's optional for others | Unique identifier of the customer for whom the virtual account is created. | | `currency` | string | Yes | ISO 4217 currency code for the virtual account (e.g., `"SGD"`). | | `country` | string | Yes | ISO 3166-1 alpha-2 country code (e.g., `"SG"` for Singapore). |