Endpoint update for mock deposit into virtual accounts

The mock deposit endpoint has been updated from {{base_url}}/api/v1/payments/mock and changed to {{base_url}}/api/v1/payments/mocks/customer-deposit

Payload remains the same. Example:

{
    "customer_id": "3a73d3c1-79f3-457d-ad88-5ce3089197174",
    "currency": "GBP",
    "amount": 400000
}