Issue:
Bug: [FEATURE]: [Iatapay] Use `connector_response_reference_id` as reference to merchant



### :memo: Feature Description

- Reference id are used to map transactions in the connector’s dashboard.
- Hyperswitch manages several reference ids, such as `payment_id`, `attempt_id`, and `connector_transaction_id` for a single transaction. 
- However, merchants may encounter uncertainty when determining which ID to utilize in the connector dashboard to identify the payment.

### :hammer: Possible Implementation

- When we receive a response from the connector for the payment, we deserialize it and populate the `response` field in RouterData. 
- For the `TransactionResponse` type, we must fill the `connector_response_reference_id` with a corresponding reference id for the merchant to identify the transaction. 
- One might need to have exposure to api docs of the connector for which it is being implemented to decide what to fill in connector_response_reference_id.
- You can check this PR for further reference https://github.com/juspay/hyperswitch/pull/1735

🔖 Note: All the changes needed should be contained within `hyperswitch/crates/router/src/connector/`


### :package: Have you spent some time checking if this feature request has been raised before?

- [X] I checked and didn't find a similar issue

### :package: Have you read the Contributing Guidelines?

- [X] I have read the [Contributing Guidelines](https://github.com/juspay/hyperswitch/blob/main/docs/CONTRIBUTING.md)

###  :sparkles: Are you willing to submit a PR?


Pull request description:
## Type of Change
<!-- Put an `x` in the boxes that apply -->

- [ ] Bugfix
- [x ] New feature
- [ ] Enhancement
- [ ] Refactoring
- [ ] Dependency updates
- [ ] Documentation
- [ ] CI/CD

## Description
<!-- Describe your changes in detail -->

- Adressess issue #2333 : Implement `connector_response_reference_id ` as reference to connector for Iatapay
- Modified the file `hyperswitch/crates/router/src/connector/iatapay/transformers.rs`
- Rebased with changes from [https://github.com/juspay/hyperswitch/commit/67cf33d0894f337839bb35b2a87d3807085e6672](url)

### Additional Changes

- [ ] This PR modifies the API contract
- [ ] This PR modifies the database schema
- [ ] This PR modifies application configuration/environment variables

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Following are the paths where you can find config files:
1. `config`
2. `crates/router/src/configs`
3. `loadtest/config`
-->


## Motivation and Context
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If it fixes an open issue, please link to the issue here.

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can focus on the implementation (unless it is an obvious bug or documentation fix
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## How did you test it?
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## Checklist
<!-- Put an `x` in the boxes that apply -->

- [ x] I formatted the code `cargo +nightly fmt --all`
- [ x] I addressed lints thrown by `cargo clippy`
- [ ] I reviewed the submitted code
- [ ] I added unit tests for my changes where possible
- [ ] I added a [CHANGELOG](/CHANGELOG.md) entry if applicable


Testing:

Patch:
diff --git a/crates/router/src/connector/iatapay/transformers.rs b/crates/router/src/connector/iatapay/transformers.rs
index 39dfd61b9a3..9d4ecdff197 100644
--- a/crates/router/src/connector/iatapay/transformers.rs
+++ b/crates/router/src/connector/iatapay/transformers.rs
@@ -212,10 +212,14 @@ impl<F, T>
         item: types::ResponseRouterData<F, IatapayPaymentsResponse, T, types::PaymentsResponseData>,
     ) -> Result<Self, Self::Error> {
         let form_fields = HashMap::new();
-        let id = match item.response.iata_payment_id {
+        let id = match item.response.iata_payment_id.clone() {
             Some(s) => types::ResponseId::ConnectorTransactionId(s),
             None => types::ResponseId::NoResponseId,
         };
+        let connector_response_reference_id = item
+            .response
+            .merchant_payment_id
+            .or(item.response.iata_payment_id);
         Ok(Self {
             status: enums::AttemptStatus::from(item.response.status),
             response: item.response.checkout_methods.map_or(
@@ -225,7 +229,7 @@ impl<F, T>
                     mandate_reference: None,
                     connector_metadata: None,
                     network_txn_id: None,
-                    connector_response_reference_id: None,
+                    connector_response_reference_id: connector_response_reference_id.clone(),
                 }),
                 |checkout_methods| {
                     Ok(types::PaymentsResponseData::TransactionResponse {
@@ -238,7 +242,7 @@ impl<F, T>
                         mandate_reference: None,
                         connector_metadata: None,
                         network_txn_id: None,
-                        connector_response_reference_id: None,
+                        connector_response_reference_id: connector_response_reference_id.clone(),
                     })
                 },
             ),