Issue:
feat(core): accept payment_confirm_source header in capture call and store in payment_intent

## Type of Change
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- [ ] Bugfix
- [x] New feature
- [ ] Enhancement
- [ ] Refactoring
- [ ] Dependency updates
- [ ] Documentation
- [ ] CI/CD

## Description
<!-- Describe your changes in detail -->
Accept payment_confirm_source header in payments confirm call and store it in payment_intent table and return in the response header.

### 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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2. `crates/router/src/configs`
3. `loadtest/config`
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## Motivation and Context
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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`
- [x] I reviewed the submitted code
- [ ] I added unit tests for my changes where possible
- [ ] I added a [CHANGELOG](/CHANGELOG.md) entry if applicable


Resolution:
<think>
PR Context:
- Title: feat(test_utils): Add custom-headers and custom delay support to rustman
- Merged: 2023-11-07T17:43:02Z
- Files changed: 4 files
- Commits: 19 commits

Implementation approach:
## Type of Change
<!-- Put an `x` in the boxes that apply -->

- [x] New feature
- [x] Documentation
- [x] CI/CD

## Description
<!-- Describe your changes in detail -->
Closes #2646 
This PR as usual, narrows the main aim of rustman by making specific to Hyperswitch. With this, you should now be able to:
- Set delay between each request sent as per your own wish while default being `7` milliseconds
- Pass in custom-headers of your wish in run time

### How custom-headers works


</think>

To implement this, you'll need to modify:


**Detailed Implementation:**


**Commit 1:** feat(test_utils): Add custom-headers and custom delay support to rustman (#2636)
Files to modify:


**crates/test_utils/src/main.rs**
  Modify existing code

**crates/test_utils/src/newman_runner.rs**
  Add:
    - function: private::insert_content
    - struct: pub::ReturnArgs