This PR essentially does multiple things in one commit. These are all quite linked to one another, I wasn't quite able to untangle them from each other.

• Refactors the existing sensor code, making encoder rotational tracking happen outside of behaviors and inside sensors.c.
• Revamps zmk_behavior_binding_event so that it is actually a zmk event, i.e. is raised and managed by event_manager.
• Allow the nesting of &trans inside of other behaviors, getting rid of ZMK_BEHAVIOR_TRANSPARENT in the process.

Taking the explanation from #573:
We currently have the following events

• position_state_changed
  • keycode_state_changed
  • layer_state_changed

What is missing from this event flow are behavior bindings. This means they can not be observed like other events.

• position_state_changed
  • behavior_binding_event
    • keycode_state_changed
    • layer_state_changed

This refactor/feat will allow for much more advanced and elegant handling in the future. My goal is to use this to rework combos a bit further. Nesting &trans is also a benefit that should not be underestimated, it will make things like home-row mods much easier to set up. The sensor refactor should allow further work on that part to be simpler as well.

Needs documentation and lots of testing, particularly around the encoder bits as the tests we have are very rudimentary. There are likely some stylistic bits that could use tidying up as well.

Closes: #573, #532, #2368

PR check-list

• Branch has a clean commit history
• Additional tests are included, if changing behaviors/core code that is testable.
• Proper Copyright + License headers added to applicable files (Generally, we stick to "The ZMK Contributors" for copyrights to help avoid churn when files get edited)
• Pre-commit used to check formatting of files, commit messages, etc.
• Includes any necessary documentation changes.