Resolve CE/EE diff in main.js

Moving ee/main.js to ee/main_ee.js allows to add a noop file in CE and
utilize ee_else_ce.

app/assets/javascripts/main.js

@@ -33,6 +33,8 @@ import GlFieldErrors from './gl_field_errors';
 import initUserPopovers from './user_popovers';
 import { __ } from './locale';
 
+import 'ee_else_ce/main_ee';
+
 // expose jQuery as global (TODO: remove these)
 window.jQuery = jQuery;
 window.$ = jQuery;

app/assets/javascripts/main_ee.js

+// This is an empty file to satisfy ee_else_ce import for the EE main entry point