When compiling with optimizations on, an issue occurs where the claimed_pins/never_reset_pins memory location is shared with another variable. This causes some bad memory read, so the USB pins ended up being reset. Setting these to have an alignment of 4 bytes resolves this.
Tested on nucleo_f746zg
Restructures the STM port of Circuitpython to be more generic about the STM32 chip lines to support
the F7 and H7 series of chips. Adds the new Packages directory to organize different chip layouts
between lines. Makes general changes to the Makefile to condense board-level flags to the minimum
and support the new chip series. Adds the new chip line to the Peripherals directory, along with
new python tools used to generate peripheral text automatically in the tools/ directory.
