Make email verification link clickable in HTML email

The HTML variant of the new email verification message rendered
emailRegistrationLink as bare text, so clients displaying the HTML
part (for example Thunderbird) showed a non-clickable URL. Wrap it
in an anchor tag, matching how other HTML templates render links.

Reported downstream at https://phabricator.wikimedia.org/T429901

Release-Notes: skip
Change-Id: I5f6870b364c669b3b150751a866dd83b24ee2022

resources/com/google/gerrit/server/mail/RegisterNewEmailHtml.soy

diff --git a/resources/com/google/gerrit/server/mail/RegisterNewEmailHtml.soy b/resources/com/google/gerrit/server/mail/RegisterNewEmailHtml.soy
index 20f9999..a485abd 100644
--- a/resources/com/google/gerrit/server/mail/RegisterNewEmailHtml.soy
+++ b/resources/com/google/gerrit/server/mail/RegisterNewEmailHtml.soy
@@ -31,7 +31,7 @@
 
   <p>
 
-    {$email.emailRegistrationLink}
+    <a href="{$email.emailRegistrationLink}">{$email.emailRegistrationLink}</a>
   </p>
   <p>
     If you have received this mail in error, you do not need to take any