Change esp32 builds to use the tflite-micro-esp-examples repo instead of building natively from tflite-micro sources

[mocleiri]

Espressif is actively maintaining the https://github.com/espressif/tflite-micro-esp-examples repository which is the Tensorflow for Microcontrollers build for esp32 using C/C++ using ESP-IDF.

Instead of depending on tflite micro directly we can depend on it as an esp-idf component which will reduce the amount of maintenance on our side and duplication.

I'm also interested in changing the build system from being submodule based to using shallow clones like ulab does it. That will allow nightly builds to run against the latest version of the different dependencies and let me notice problems earlier.

As part of this I want to upgrade to the latest micropython master (>1.20.0) to address #125 and #111.

[mocleiri]

I was having trouble getting the github action build to work due to hitting the ARG_MAX limit in ubuntu. Essentially there is a limit on the character buffer for command line arguments and because of the nested depth of the checked out code it was hitting the limit and failing the QSTR generation.

I found a fix in that I can just move the checked out sources up a level which reduces the text usage for each path by 25ish characters and comes in under the limit.