HID refactoring

[kaczmarczyck]

This PR has 2 commits. The first

• introduces the CtapHidCommand enum
• splits off logic to parse Messages with a new process_message that contains core logic
• fixes the documentation

After this bigger cleanup, the second commit actually works on the goal of this PR: To have an API that separates all CTAP logic, and is the first step on the road to a pure HID library. It does so without changing the API. The plan is to move process_hid_packet (which is now very short) out of the library, and have two instances with different process_message functions later. This will also allow removing the wink_permission eventually.

If you rather review in 2 PRs, I'll split the second commit to a new PR (or I could also split commit 1 if necessary). In this case, consider this the overview.

Plan for future submissions is:

• Refactor the tests in hid/mod.rs, the new interface is much more test friendly.
• Do the aforementioned move to make this a pure library (possible multiple steps actually).
• Introduce the second USB transport.

[kaczmarczyck]

The fuzzing check passes locally, therefore I'll submit and fix that separately.

[ia0]

The fuzzing check passes locally, therefore I'll submit and fix that separately.

Note also that it's the CIFuzz job that's failing, not the "Cargo fuzz build" one, so it's working locally even for GitHub. It's the docker setup the issue.