WICKET-5729 Avoid using input names that conflict with JavaScript DOM API method and attribute names

Fix the selectors in the Gym.js tests
Move the Apache license test for wicket-util from src/main to src/test
WICKET-5746 Fire an event once all JS event listeners are registered

Fire Wicket.Event.Topic.AJAX_HANDLERS_BOUND event once all Wicket.Ajax.ajax() calls are executed