This moves badge hardware generation selection over from a header file
into ESP-IDF configuratbility.

The generaiton can now be selected by specifying `BADGE_GENERATION` or
`-g` when running the initial built.

In addition, each generation now gets its own sdkconfig.defaults file
(instead named sdkconfig.$generation) and the big autogeneration
sdkconfig file gets yeeted.

This moves the badge23-specific hardware/synth modules into usermodule/.

This refactors the build system to be more in line with the average
ESP-IDF project.

This means that:
  1. `idf.py` from the main directory now works
  2. Adding components, running menuconfig, etc. should now be trivial.
  3. We don't have to edit files in micropython/ports/esp32/....

Hopefully this is the first step to yeeting the micropython checkout
from source and just depending on a submodule instead.