Add 4 new browser snippets

triggerEvent - trigger an event on an element, insertAfter & insertBefore - parse and insert HTML after or before an element respectively, elementContains - checks if an element contains another element

test/triggerEvent/triggerEvent.js

@@ -0,0 +1,2 @@
+const triggerEvent = (el, eventType, detail = undefined) => el.dispatchEvent(new CustomEvent(eventType, {detail: detail}));
+module.exports = triggerEvent;