feat(editorconfig): add builtin EditorConfig support

runtime/plugin/editorconfig.lua

@@ -0,0 +1,11 @@
+if vim.g.editorconfig_enable == false or vim.g.editorconfig_enable == 0 then
+  return
+end
+
+local group = vim.api.nvim_create_augroup('editorconfig', {})
+vim.api.nvim_create_autocmd({ 'BufNewFile', 'BufRead', 'BufFilePost' }, {
+  group = group,
+  callback = function(args)
+    require('editorconfig').config(args.buf)
+  end,
+})