Restructure Darwin configuration

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

modules/hosts/common/files/nvim/lua/disabled/themes/gruvbox.lua

@@ -0,0 +1,11 @@
+return  {
+  "ellisonleao/gruvbox.nvim",
+  priority = 1000 ,
+  config = function ()
+    require("gruvbox").setup()
+
+    vim.o.background = "dark"
+    vim.o.termguicolors = true
+    vim.cmd.colorscheme "gruvbox"
+  end
+}