hwctl needs to show me EXACTLY what is being sent

### Check existing issues

- [x] I've verified that this request isn't described by any existing issues.

### Request

If I am going to voluntarily send my hardware data (assurances of no identifiers aside) I want to see the payload being sent, without having to trap teh outgoing packets and inspecting them that way. And believe me, because we are making this a direct part of ubuntu, people WILL inspect it to that level once this is part of Ubuntu.

I should be able to pass a debug flag or something to hwctl that then shows me exactly what is being sent to Canonical on my behalf.

We have had a few different things over the years that phone home, and they always seem to stir up some manner of hornets nest: Popcon, Amazon links in search results, a "use checkbox at home and register your results with Certification" effort many years ago, etc.

### Motivation

To see exactly what my machine and hwctl are sending back to Canonical on my behalf to make an informed decision.

Start by locating the hwctl command entry point and the code that constructs its outgoing hardware payload. Determine how a debug option should expose the exact payload without changing normal submission behavior, then verify the displayed data matches what is sent and add or run the relevant CLI tests.

Written by the indexing model from the issue text.