Add Raspberry Pi 4 Compute Module
I've followed the footprint for Raspberry Pi Zero that's already present in the library.
Symbol: kicad-symbols!4159
Datasheet/Pin layout: https://datasheets.raspberrypi.com/cm4/cm4-datasheet.pdf (page 17, ConChapter 4)
Connector: https://download.kamami.pl/p585040-ed_DF40_20200205.pdf (DF40C-100DS-0.4V)
Edited by Petr Hodina