Issue:
[ENHANCEMENT] Add connector_label field in error type

### Feature Description

A `DuplicateMerchantConnectorAccount` will occur when inserting a row in the `merchant_connector_account` table if there is a row that already exists with the same merchant_id and connector_label. The connector_label is created by Hyperswitch internally hence it is necessary to send back the connector_label is the error response so that the user has an idea of what the connector_label is.  

### Possible Implementation

add a field connector_label in the error message of `DuplicateMerchantConnectorAccount`.

### 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?

None

Resolution:
<think>
PR Context:
- Title: refactor(router): add the `connector_label` field to `DuplicateMerchantConnectorAccount` error message
- Merged: 2023-05-04T14:29:59Z
- Files changed: 3 files
- Commits: 2 commits

Implementation approach:
## Type of Change
<!-- Put an `x` in the boxes that apply -->

- [ ] Bugfix
- [ ] New feature
- [ ] Enhancement
- [x] Refactoring
- [ ] Dependency updates
- [ ] Documentation
- [ ] CI/CD

## Description
<!-- Describe your changes in detail -->
This PR adds the connector_label to the message of the DuplicateMerchantConnectorAccount variant in the ApiErrorResponse enum


### Additional Changes

- [ ] This PR modifies the API contract
- [ ] This PR modifies the database schema
-
</think>

To implement this, you'll need to modify:


**Detailed Implementation:**


**Commit 1:** refactor(router): add the `connector_label` field to `DuplicateMerchantConnectorAccount` error messa
Files to modify:


**crates/router/src/compatibility/stripe/errors.rs**
  Modify existing code

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

**crates/router/src/core/errors/api_error_response.rs**
  Modify existing code