Use navigator.userAgentData in Chrome version page

navigator.userAgent will be deprecated in Chrome 101, so this CL makes
the JS code use navigator.userAgentData to keep retrieving the browser
version, while keeping the deprecated way as a fallback.

In order to simplify the logic now the page only shows the version for
Chrome, and doesn't work with other browsers.

Also, due to the complexity of parsing the Chrome iOS user agent string,
this OS isn't supported yet.

Fixed: misc:43
Change-Id: I23e7221318013afb3b1bba738e9c07851ea1692f
diff --git a/overrides/versionpage.html b/overrides/versionpage.html
index 26dbb0b..40443e5 100644
--- a/overrides/versionpage.html
+++ b/overrides/versionpage.html
@@ -53,5 +53,6 @@
   This is working as intended, since this also makes the page load faster.
 {% block scripts %}
+  <script src="{{ 'assets/javascripts/ua_utils.js' | url }}"></script>
   <script src="{{ 'assets/javascripts/version_page.js' | url }}"></script>
 {% endblock %}