feat: messages extension (#4028)

* feat: private messages

extensions/messages/.editorconfig

@@ -0,0 +1,19 @@
+# EditorConfig helps developers define and maintain consistent
+# coding styles between different editors and IDEs
+# editorconfig.org
+
+root = true
+
+[*]
+end_of_line = lf
+charset = utf-8
+trim_trailing_whitespace = true
+insert_final_newline = true
+indent_style = space
+indent_size = 2
+
+[*.{diff,md}]
+trim_trailing_whitespace = false
+
+[*.{php,xml,json}]
+indent_size = 4