feat: Do not depend on user config | Fix merging of configs

because it is a user config, so our config shoudn't break even we if dont have it

use our own table merge function

move loading config to a function

use a global variable to store the config, so no need to call the table function everytime

lua/theme.lua

@@ -1,4 +1,4 @@
-local chad_theme = require("chadrc").ui.theme
+local chad_theme = require("utils").load_config().ui.theme
 vim.g.nvchad_theme = chad_theme
 
 local present, base16 = pcall(require, "base16")