This implements a st3m-specific USB stack. It's effectively what
espressif provides with their esp_tinyusb component, but allows for
dynamic reconfiguration of the USB device.

This comes form the ESP component registry, but we just want to vendor
the code instead of relying on package management.

Plus, we need to hack CMakeLists.txt to make it work with our setup, for
some reason. Otherwise we don't get callbacks...

Hacking on things is fun, but accidentally doing machine.Pin(1337).on()
and frying your flow3r isn't. Especially if you're just copypasting code
from the Internet.

We might add some escape hatch for this later for board
experimentation/testing/debugging..?

We don't care for it much in our usecase, and it reduces performance.

At least I think so. We might want to roll this back later :).

This doesn't seem to be less performant than the rube goldberg we had
previously, but somehow fixes up rendering glitches.

Phew.

This was mostly blocked by Micropython, but it has since then also
upgraded to IDF 5: https://github.com/micropython/micropython/commit/e4650125b88a35f074097f16d84a8f49bd22ac06

We take that change and selectively apply it where necessary. However,
it's not a 1:1 patch apply, as we already were on a somewhat forked
Micropython, and we also want to support IDF 5.1, not 5.0.

We also bump up the IDF distribution brought in by Nix, and fix some
warnings that have since turned into errors due to toolchain changes.

This is replaced by more mpy-centric code for user interaction plus
bl00mbox for the actual sound framework.

We already moved LEDs to their own task. Let's try doing that for
jacksense too. As long as we don't run out of RAM this should be better
than having larger tasks, as things won't block eachother that much..?

1. Add locking (st3m_audio_* functions are now thread/task-safe).
2. Remove some duplicate code around speaker/headphones output.
3. Simplify applying audio volume to codec ('apply' function).
4. Small style stuff (bool, etc).