Make APIs better

[Ottatop]

Well my right middle finger's knuckle is still sore from no-lifeing Celeste so I decided to work on this thing instead we are so back baby

This PR is intended to be the big final breaking change to the Lua and Rust APIs until 0.1 is released. As a result, this PR is going to be way too big and cover the following aspects:

• Update the protobuf from proto2 to proto3
• Better window rule API
• Better layout API
  • Not a fan of how the client is expected to calculate its own rects for layouting; this means I have to duplicate all the logic over Lua and Rust, and it doesn't support resizing tiles
  • Something compositor-side is gonna be needed
  • Alternatively push this off to some future update
• Better output management API, or simply remove the current one and direct you to something like kanshi until I can figure something out
• Better process API
  • Better spawning API for Rust that mirrors std::process::Command
  • Something akin to awful.spawn.once so you can spawn things on startup, close them, and not have them respawn on config reload
• Better libinput API
• Better key- and mousebind API
• Hide the snowcap API until it's actually somewhat stable
• Probably a bunch of other things
• And try to fix all the FIXMEs you left everywhere
• And update the config gen cli
• And remember to do that "let xwayland scale itself" thing pushing off to later

Side note: I regret deciding to do a Rust API because wow is it not fun to try to design something remotely ergonomic haha nvm this is kinda fun

Edit: hey past me it's present me here to tell you to:

• Add docs for the move from metaconfig.toml to pinnacle.toml
• Add docs for the new input API
• DOCS SOON I SWEAR
• Oh and do this all again for the Lua side 👍

[Ottatop]

Closes #138