Restructure Darwin configuration

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

modules/hosts/common/files/nvim/lua/plugins/none-ls.lua

@@ -0,0 +1,40 @@
+return {
+	{
+		"jay-babu/mason-null-ls.nvim",
+		event = { "BufReadPre", "BufNewFile" },
+		dependencies = {
+			"williamboman/mason.nvim",
+			"nvimtools/none-ls.nvim",
+		},
+		config = function()
+			require("mason-null-ls").setup({
+				ensure_installed = {
+					"prettier", -- HTML, JS, JSON, etc.
+					"stylua", -- LUA
+				},
+			})
+		end,
+	},
+	{
+		-- none-ls replaces null_ls... it's weird
+		"nvimtools/none-ls.nvim",
+		dependencies = { "nvim-lua/plenary.nvim" },
+		config = function()
+			local null_ls = require("null-ls")
+
+			null_ls.setup({
+				sources = {
+					null_ls.builtins.completion.spell,
+					null_ls.builtins.diagnostics.puppet_lint,
+					null_ls.builtins.diagnostics.rubocop,
+					null_ls.builtins.formatting.prettier,
+					null_ls.builtins.formatting.puppet_lint,
+					null_ls.builtins.formatting.rubocop,
+					null_ls.builtins.formatting.stylua,
+				},
+			})
+
+			vim.keymap.set("n", "<leader>gf", vim.lsp.buf.format, {})
+		end,
+	},
+}