plugins: More lazy load, yay

use vim.defer_fn to load the plugins after entering the ui

add the lazy load to setup

lazy load gitsigns, neoscroll, lspinstall and vim-matchup using this method

rearrange according to startup sequence

lua/core/utils.lua

@@ -310,4 +310,14 @@ end]]
    return into
 end
 
+-- load plugin after entering vim ui
+M.packer_lazy_load = function(plugin, timer)
+   if plugin then
+      timer = timer or 0
+      vim.defer_fn(function()
+         require("packer").loader(plugin)
+      end, timer)
+   end
+end
+
 return M