Adopt recent changes, migrate product detail page

public/typo3conf/ext/ep_events/Configuration/TypoScript/Page/Main.typoscript

@@ -11,12 +11,6 @@ page {
         main = typo3_encore:EpEventsConfig:main
     }
 
-    includeJS {
-        remarketing = https://www.googleadservices.com/pagead/conversion_async.js
-        remarketing.external = 1
-        remarketing.disableCompression = 1
-    }
-
     includeJSFooter {
         main = typo3_encore:EpEventsConfig:main
     }
@@ -73,6 +67,17 @@ page {
         }
     }
 
+    headerData.998 = TEXT
+    headerData.998.value (
+        <!-- Google Tag Manager -->
+        <script type="text/plain" data-cookiefirst-category="functional">(function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':
+        new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],
+        j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src=
+        'https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);
+        })(window,document,'script','dataLayer','{$plugin.tx_epevents.settings.googleTagManagerId}');</script>
+        <!-- End Google Tag Manager -->
+    )
+    headerData.998.stdWrap.if.isTrue = {$plugin.tx_epevents.settings.googleTagManagerId}
 
     headerData.999 = TEXT
     headerData.999 {