fix(middleware): include `x-request-id` header in `access-control-expose-headers` header value

## Type of Change
<!-- Put an `x` in the boxes that apply -->

- [x] Bugfix
- [ ] New feature
- [ ] Enhancement
- [ ] Refactoring
- [ ] Dependency updates
- [ ] Documentation
- [ ] CI/CD

## Description
<!-- Describe your changes in detail -->
This PR fixes a bug where `x-request-id` was not being included in the `access-control-expose-headers` header. The solution is to register the request ID middleware before the CORS middleware.

## Motivation and Context
<!--
Why is this change required? What problem does it solve?
If it fixes an open issue, please link to the issue here.

If you don't have an issue, we'd recommend starting with one first so the PR
can focus on the implementation (unless its an obvious bug or documentation fix
that will have little conversation).
-->
Bugfix.

## How did you test it?
<!--
Did you write an integration/unit/API test to verify the code changes?
Or did you test this change manually (provide relevant screenshots)?
-->
Before:

```shell
$ curl -i http://localhost:8080/health
[...]
access-control-expose-headers: via, strict-transport-security
[...]
```

After:
```shell
$ curl -i http://localhost:8080/health
[...]
access-control-expose-headers: x-request-id, via, strict-transport-security
[...]
```

## 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 submitted code
- [ ] I added unit tests for my changes where possible
- [ ] I added a [CHANGELOG](/CHANGELOG.md) entry if applicable

<think>
PR Context:
- Title: fix(cors): expose all headers set by application in `access-control-expose-headers` header value
- Merged: 2024-12-24T07:04:04Z
- Files changed: 1 files
- Commits: 1 commits

Implementation approach:
## Type of Change
<!-- Put an `x` in the boxes that apply -->

- [x] Bugfix
- [ ] New feature
- [ ] Enhancement
- [ ] Refactoring
- [ ] Dependency updates
- [ ] Documentation
- [ ] CI/CD

## Description
<!-- Describe your changes in detail -->

This PR exposes all headers set by the application in the `access-control-expose-headers` header value. This should thus allow our headers like `x-request-id` to be accessed by the browser.

## Motivation and Context
<!--
Why is this cha
</think>

To implement this, you'll need to modify:


**Detailed Implementation:**


**Commit 1:** fix(cors): expose all headers set by application in `access-control-expose-headers` header value (#6
Files to modify:


**crates/router/src/cors.rs**
  Modify existing code
{"issue_number": 1673, "pr_number": 6877, "commits_count": 1, "files_changed": 1, "response_length": 1001, "file_count": 3, "needs_breakdown": false}