Rewrite Neovim config

[tomodachi94]

The current configuration is a mess:

• Some of the configuration was "glue-code" for my non-NixOS system, and now it either conflicts or is redundant on NixOS. Examples: d713b7ed8ce957e32efd9d2dcadb0a48b36c4bde and b64f05edf8418ec03e117bb2e5e47a374d50ee70
• Configuration for plugins is spread out vastly and inconsistently, causing the code to be inconsistent with the style of the other parts of the repo.
• Much of the code was copy-pasted from other sources, leading to a very inconsistent code style. (I don't even remember what some of it does!)
  • Some mysterious Vimscript is floating around, and I don't know what it does...
• Various breakages, such as #6

Tasks

• [ ] Use Neovim nightly
  • We can then drop plugin/ftdetect/mcmeta.lua
• [ ] Add quality control measures (linting and testing)
• [ ] Identify and add plugins missing from Nixpkgs
• [ ] Devise a new organizational scheme for organizing plugins: one per file? One per 'concern'? One big file?
• [ ] Port over non-plugin configuration:
  • [ ] util.lua
  • [ ] options.lua
  • [ ] keybinds.lua
• [ ] Rewrite "plugin modules" to use lz.n, or drop them if they won't be missed:
  • [ ] autocompletion.lua
  • [ ] autoinsert.lua
  • [ ] extras_movement.lua
  • [ ] lsp.lua
  • [ ] mason.lua
  • [ ] notifications.lua
  • [ ] snippets.lua
  • [ ] status_bar.lua
  • [ ] support_editorconfig.lua
  • [ ] support_elixir.lua
  • [ ] support_mediawiki_editor.lua
  • [ ] syntax.lua
  • [ ] thanks.lua
  • [ ] theme.lua
  • [ ] tools.lua