Rewrite STM32 blinky to easily add other boards/chips. #179

Job	Run time
Build Website	19s
Dry Run Packaging	1m 0s
Build Examples (espressif/esp)	2m 13s
Build (ubuntu-latest)	32s
Build Examples (gigadevice/gd32)	2m 8s
Check that stm32 generated code is up to date	45s
Build (windows-latest)	1m 46s
Build Examples (microchip/avr)	2m 11s
Unit Test Ports (ubuntu-latest, gigadevice/gd32)	16s
Build (macos-latest)	28s
Unit Test Ports (ubuntu-latest, raspberrypi/rp2xxx)	14s
Build Examples (microchip/atsam)	2m 5s
Unit Test Ports (ubuntu-latest, stmicro/stm32)	21s
Unit Test Regz (ubuntu-latest)	23s
Build Examples (nordic/nrf5x)	2m 0s
Unit Test Ports (windows-latest, gigadevice/gd32)	1m 43s
Unit Test Regz (windows-latest)	1m 7s
Build Examples (nxp/lpc)	2m 3s
Unit Test UF2 (ubuntu-latest)	16s
Unit Test Ports (windows-latest, raspberrypi/rp2xxx)	1m 8s
Unit Test Regz (macos-latest)	23s
Build Examples (stmicro/stm32)	19s
Unit Test UF2 (windows-latest)	1m 32s
Unit Test Ports (windows-latest, stmicro/stm32)	1m 41s
Build Examples (raspberrypi/rp2xxx)	2m 28s
Unit Test UF2 (macos-latest)	27s
Unit Test Ports (macos-latest, gigadevice/gd32)	18s
Build Examples (wch/ch32v)	2m 12s
Unit Test Ports (macos-latest, raspberrypi/rp2xxx)	47s
Unit Test Ports (macos-latest, stmicro/stm32)	26s
	33m 31s

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