[V2] - Not returning a meaningful error for payload validation failures in payment initiation

[malshaniS]

Getting a common error message which is not meaningful for the specific payload validation error in payment initiation flow.

Test Cases:
TC0401020_Initiation Request without debtorAccount in the payload
Expected Error: "Object has missing required properties ([\"debtorAccount\"])"

TC0401021_Initiation Request without payments in the payload
Expected Error: "Object has missing required properties ([\"payments\"])"

TC0401027_Initiation Request with empty debtorAccount in the payload
Expected Error: "ECMA 262 regex \"[A-Z]{2,2}[0-9]{2,2}[a-zA-Z0-9]{1,30}\" does not match input string"

TC0401029_Initiation Request with empty array elements for payments