Issue:
[FEATURE]: [PayU] 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?


Resolution:
<think>
PR Context:
- Title: feat(connector): [PayU] Use connector_response_response_id as reference to merchant
- Merged: 2023-10-05T19:21:01Z
- Files changed: 1 files
- Commits: 15 commits

Implementation approach:
## Type of Change
<!-- Put an `x` in the boxes that apply -->

- [ ] Bugfix
- [x] New feature
- [ ] Enhancement
- [ ] Refactoring
- [ ] Dependency updates
- [ ] Documentation
- [ ] CI/CD

## Description
Fixes #2344 


### Additional Changes

- [ ] This PR modifies the API contract
- [ ] This PR modifies the database schema
- [ ] This PR modifies application configuration/environment variables

<!--
Provide links to the files with corresponding changes.

Following are the 
</think>

To implement this, you'll need to modify:


**Detailed Implementation:**


**Commit 1:** feat(connector): [PayU] Use connector_response_response_id as reference to merchant (#2452)
Co-autho
Files to modify:


**crates/router/src/connector/payu/transformers.rs**
  Modify existing code