init: Asynchronously load filetype and syntax

lots of improvement for startup time

Co-authored-by: Vhyrro <vhyrro@gmail.com>

lua/options.lua

@@ -1,6 +1,13 @@
 local opt = vim.opt
 local g = vim.g
 
+-- Turn these off at startup, will be enabled later just before loading the theme
+vim.cmd([[
+    syntax off
+    filetype off
+    filetype plugin indent off
+]])
+
 opt.ruler = false
 opt.hidden = true
 opt.ignorecase = true