WIP: mainboards: Add Google Octopus Bobba board

[rmsyn]

Add support for the Acer Chromebook Cb311-9h mainboard.

Most of the code is a more-or-less direct port from coreboot, with some modifications to make the code more Rust-y.

Code could probably still use a lot of cleanup, and may have missing parts (still unsure of the multistage build in coreboot).

Code also brings back Intel FSP, which accounts for a substantial amount of lines of code.