Allow custom compiled in code.py contents

[todbot]

This PR allows a one-line code.py to be specified in a port's mpconfigboard.mk so a product's full firmware can be built in CI. The intended use is something like the following in mpconfigboard.mk:

FROZEN_MPY_DIRS += $(TOP)/ports/raspberrypi/boards/raspberry_pi_pico_todbot
CIRCUITPY_CODEPY_CONTENTS="import some_awesome_code\n"

and then some_awesome_code.py located in the port's directory contains what would normally be code.py.
(I would rather we have the ability to specify a folder to copy over with code.py, /lib, settings.toml, etc. but this is what I've been using internally for some projects)

[dhalbert]

People have been doing this "by hand" before. This is fine with me.

[tannewt]

This would be ok with me but I'm not sure it is actually what you want. These are really default contents that are stored forever in the firmware. Instead, I suspect you want an easy way to provide a CIRCUITPY image to install alongside a version of CircuitPython. #10074 is a better place to discuss options.

I suspect this will crash the Zephyr ports because they don't use make and won't have the new define. We should test that if we want to actually merge this.

[todbot]

[...] I suspect you want an easy way to provide a CIRCUITPY image to install alongside a version of CircuitPython. #10074 is a better place to discuss options.

Yep, as mentioned in #10074 having a CIRCUITPY image maker is really what's wanted. This PR was a stop-gap to solve the problem I've seen people ask for (and I've been using) for several years.

[tannewt]

Are you ok if I close this PR then?

[todbot]

Sure I guess. I'll continue to maintain my fork that has this patch for my own work since it seems others don't want this.