Restructure Darwin configuration

So far, this is just based on mightymac. The other devices will be
updated soon.

modules/home-manager/files/nvim/lua/plugins/neo-tree.lua

@@ -1,24 +0,0 @@
-return {
-  "nvim-neo-tree/neo-tree.nvim",
-  lazy = false,
-  branch = "v3.x",
-  dependencies = {
-    "nvim-lua/plenary.nvim",
-    "nvim-tree/nvim-web-devicons",
-    "MunifTanjim/nui.nvim",
-  },
-  config = function()
-    vim.g.loaded_netrw = 1
-    vim.g.loaded_netrwPlugin = 1
-    vim.keymap.set("n", "<C-n>", ":Neotree toggle<CR>", {})
-    require("neo-tree").setup({
-      filesystem = {
-        follow_current_file = {
-          enabled = true,
-        },
-        hijack_netrw_behavior = "open_default",
-      },
-      follow_current_file = { enabled = true },
-    })
-  end,
-}