Add Hardware-In-the-Loop (HIL) testing to MicroPython

[mattytrentini]

It is highly desirable to use HIL testing in the CI pipeline of MicroPython. Tests could be run on a number of devices which would give a high degree of confidence of a successful build if the tests had adequate coverage.

Todo

• Set up a PC
• Set up a self-hosted runner and connect it to upstream
• Connect devices to the PC
• Make devices available to build containers
• Create tests (maybe start with micropython-test-port?)
• Execute tests on all devices

May be best to change MicroPython to build and store some firmware in the main repository (so the firmware binaries wouldn't need rebuilding).