Issue:
[ENHANCE] Send connector in refund response 

### Feature Description

Add field connector in `api_models::refunds::RefundResponse`. 

### Possible Implementation

We store connector field in `storage_models::Refund`. Map it to the field in `RefundResponse`

### Have you spent some time to check if this feature request has been raised before?

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

### Have you read the Contributing Guidelines?

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

### Are you willing to submit a PR?

Yes I am willing to submit a PR!

Resolution:
<think>
PR Context:
- Title: feat(refunds): add connector field in refund response
- Merged: 2023-05-09T15:36:46Z
- Files changed: 2 files
- Commits: 2 commits

Implementation approach:
## Type of Change
<!-- Put an `x` in the boxes that apply -->

- [ ] Bugfix
- [ ] New feature
- [x] Enhancement
- [ ] Refactoring
- [ ] Dependency updates
- [ ] Documentation
- [ ] CI/CD

## Description
<!-- Describe your changes in detail -->
Added connector field in refund response. We have connector field in storage model of Refund but don't return it in Refund response. Add it in refund response gives context as to which connector was called for refund(same connector through whi
</think>

To implement this, you'll need to modify:


**Detailed Implementation:**


**Commit 1:** feat(refunds): add connector field in refund response (#1059)
Co-authored-by: Sarthak Soni <76486416
Files to modify:


**crates/api_models/src/refunds.rs**
  Modify existing code

**crates/router/src/core/refunds.rs**
  Modify existing code