docs: add documentation comments to most functions

feat: implement usb devicd cdc descriptors, init, setup

feat: move all sending instructions to generic send functions

fix: make sure to error if endpoint id not found in interrupt

This generally shouldn't happen,
but it needs to be ensured that the
memory at incorrect place won't be read
or written to!
Otherwise there could be undefined behavior!
This would possibly write to the fifos,
meaning the data the usb sends could be
different than what the application intended!

fix: clear bit operation

feat: implement most of enumeration

feat: receive setup packets

feat: implement simple control usb read, writes

wip: usb

chore: some renames

fix: into_alternate choose alternate mode

feat: rewrite main to use types

feat: add registers, pin, exti, usb_device skeleton

feat: add support for newlib

feat: toggle led on exti interrupt push button

feat: use cmsis for register definitions

Initial commit (template)