ST7920 display driver

For esp-idf since there's no fucking driver for it appearently

Ngl a clanker wrote most of it, thx claude. I made it better, cleaner, more optimized (?) and more readable. The clanker got it to work but man the code was ass.

It's geared to work with my own gfx library, it exposes draw/clear pixel funcs. Nothing else, other than basic init functions and backlight.

Todo

• idk add backlight pwm? it does work fine rn