enable msgpack in zephyr port and add test for it. fix unpack issue

[FoamyGuy]

Enabled msgpack core module in the zephyr port and added test_msgpack.py to validate its functionality. I'm wondering if there is something else I need to do to get the rest of the autogen files to update? The only ones committed in this branch are the two devices that I built.

The test was initially failing when run on the native sim but passing when run on hardware. Claude assisted debug points to the issue being that the calls like mp_obj_dict_store(d, unpack(s, ext_hook, use_list), unpack(s, ext_hook, use_list)); do not guarantee the evaluation order of function arguments. So the compiler could evaluate them in the unintended order which was leading to dictionaries coming out as {value: key} instead of {key: value}. The fix is to split that statement up and call unpack in the intended order explicitly.

[tannewt]

I'm wondering if there is something else I need to do to get the rest of the autogen files to update?

I usually run make all (there is make clean-all too.)

do not guarantee the evaluation order of function arguments.

Whoa! I did not know that. Python does left-to-right: https://docs.python.org/3/reference/expressions.html#evaluation-order

[tannewt]

Looks good! Thank you!