fixed various bugs and added new commands

fixed bit shifting bug where half of the gpio pins were read instead of write :(, added simple serial interface + clock based waiting instead of busy loops

reading bytes from sst39 now works!

read/write operations

split address bus on gpio E and D, and added bitwise operations accordingly. data pins and address pins work well now.

oop for the flash structure, r/w to pins

oops forgot to add main

rcc configs, send power to gpiod, setup gpio

added serial interface