Add dependents ("via ..." comments) in export command (#12350)

Adding dependency trace/parent comments ("via ...") to the export
command output.
This is a similar behavior to the pip compile output.

#### Note to the eager reviewer:
First of all - thanks!  
Secondly, this is still a very rough draft. These are the first lines of
code I've ever written in Rust. This is still mostly an educational/fun
exercise for myself. If opening a Draft PR is creating too much noise -
I apologize and I will close it until it is ready.

## Summary

Resolves #7777

## Test Plan

- [X] manual command execution
- [x] update expected output in tests

---------

Co-authored-by: Charlie Marsh <charlie.r.marsh@gmail.com>

docs/reference/cli.md

@@ -2418,6 +2418,8 @@ uv export [OPTIONS]
 <p>However, in some cases, you may want to use the platform&#8217;s native certificate store, especially if you&#8217;re relying on a corporate trust root (e.g., for a mandatory proxy) that&#8217;s included in your system&#8217;s certificate store.</p>
 
 <p>May also be set with the <code>UV_NATIVE_TLS</code> environment variable.</p>
+</dd><dt id="uv-export--no-annotate"><a href="#uv-export--no-annotate"><code>--no-annotate</code></a></dt><dd><p>Exclude comment annotations indicating the source of each package</p>
+
 </dd><dt id="uv-export--no-binary"><a href="#uv-export--no-binary"><code>--no-binary</code></a></dt><dd><p>Don&#8217;t install pre-built wheels.</p>
 
 <p>The given packages will be built and installed from source. The resolver will still use pre-built wheels to extract package metadata, if available.</p>