Whoops.

This allows us to os.listdir("/").

Fixes #12.

We attempt to share st3m with the recovery firmware, and thus must
eliminate two components that can't live in the recovery firmware:

1. The startup function, which contains references to all matters of
   subfunctionality we don't want (audio, micropython, etc)
2. The FS code, which contains references to the tarball extraction
   logic (which we don't want to embed into recovery mode either).

Previously MicroPython would mount LittleFS directly from the partition
by itself, using its own VFS stack.

This reconfigured the VFS layer in MicroPython to use POSIX
open/read/write/etc calls, which are backed by ESP-IDF. Now, instead of
managing (possibly multuple) block devices at different mountpoints,
MicroPython simply passes through all VFS access to the ESP-IDF VFS.

Then, we make the ESP-IDF VFS mount a wear-leveled FAT (backed by the
same partition which previously held LittleFS) onto /.

This is an annoyingly large change, but the gist of it is that we:

1. Move ctx into components/ctx
2. Move uctx into usermodule/mp_uctx.c
3. Split out uctx config into ctx_config.h and share it with the
   simulator.
4. Delete a bunch of unused ctx files
5. Flip some ctx bits for speed.
6. Draw the rest of the owl, ie. implement a dedicated rasterizer task
   in components/st3m.

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.