Enhance Header and Layout components with new features and scripts

- Filtered out the Contact link from the main navigation in Header.astro and added a Contact icon that links to the contact page.
- Integrated Rocket.Chat Livechat script into Layout.astro for improved user support interaction.

src/layouts/Layout.astro

@@ -73,5 +73,15 @@ const { language, textDirection } = I18N;
     <LanguagePersistence />
     <CookieBanner />
     <BackToTop />
+    <!-- Start of Rocket.Chat Livechat Script -->
+    <script type="text/javascript">
+      (function(w, d, s, u) {
+        w.RocketChat = function(c) { w.RocketChat._.push(c) }; w.RocketChat._ = []; w.RocketChat.url = u;
+        const h = d.getElementsByTagName(s)[0], j = d.createElement(s);
+        j.async = true; j.src = 'https://chat.365devnet.eu/livechat/rocketchat-livechat.min.js?_=201903270000';
+        h.parentNode.insertBefore(j, h);
+      })(window, document, 'script', 'https://chat.365devnet.eu/livechat');
+    </script>
+    <!-- End of Rocket.Chat Livechat Script -->
   </body>
 </html>