- Updated HAProxy configuration template to set all standard proxy headers for HTTP requests.
- Added support for a unique request ID via `unique-id-format` and `unique-id-header` directives.
- Implemented E2E tests for header validation, request correlation, and configuration correctness.
- Enhanced documentation to explain usage and examples of proxy headers.
- Updated CI workflows to include E2E tests for proxy headers.
- Relocated all files and scripts from `examples` to `tests_e2e` for better organization.
- Updated references and paths in configurations, scripts, and test files.
- Adjusted `bump-version.sh` to handle the new `tests_e2e` structure.
- Updated `.gitignore` to reflect path changes.
