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

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
• Oh and do this all again for the Lua side 👍