feat: freeze all python code, restructure build

Add all python code run on the device to the manifest.py to freeze
it. This has two benefits:
- It precompiles the bytecode, so it is smaller and faster
- All code (C and python) is now in the firmware image, leaving the
  littlefs filesystem on the flash free for user settings.

This requires changing the way the hardware variants are handled. There
is now only one _filesystem_ image, but instead there are different
_firmware_ images for each variant.

Signed-off-by: Matthias Blankertz <matthias@blankertz.org>

software/boards/RPI_PICO_W/manifest.py

@@ -15,3 +15,10 @@ module("microdot.py", "../../lib/microdot/src/microdot/")
 # TonberryPico modules
 module("audiocore.py", "../../modules/audiocore")
 module("rp2_neopixel.py", "../../modules")
+
+module("main.py", "../../src")
+module("app.py", "../../src")
+module("mp3player.py", "../../src")
+module("webserver.py", "../../src")
+package("utils", base_path="../../src")
+package("nfc", base_path="../../src")