Added gtag script

Author: Quentin Alldredge

layouts/partials/extend-head.html

@@ -0,0 +1,13 @@
+  <script>
+  window.dataLayer = window.dataLayer || [];
+  function gtag() { dataLayer.push(arguments); }
+  gtag('consent', 'default', {
+    'ad_user_data': 'denied',
+    'ad_personalization': 'denied',
+    'ad_storage': 'denied',
+    'analytics_storage': 'granted',
+    'wait_for_update': 500,
+  });
+  gtag('js', new Date());
+  gtag('config', 'G-1KX8P933JG');
+  </script>

static/js/gtag.js

@@ -0,0 +1,18 @@
+  grantButton.addEventListener("click", function() {
+  localStorage.setItem("consentGranted", "true");
+  function gtag() { dataLayer.push(arguments); }
+
+  gtag('consent', 'update', {
+    ad_user_data: 'granted',
+    ad_personalization: 'granted',
+    ad_storage: 'granted',
+    analytics_storage: 'granted'
+  });
+
+  // Load gtag.js script.
+  var gtagScript = document.createElement('script');
+  gtagScript.async = true;
+  gtagScript.src = 'https://www.googletagmanager.com/gtag/js?id=G-1KX8P933JG';
+
+  var firstScript = document.getElementsByTagName('script')[0];
+  firstScript.parentNode.insertBefore(gtagScript,firstScript);