Split codesearch builders onto their own master

masters/master.chromium.infra.codesearch/templates/announce.html

 {% extends "layout.html" %}
 
 {% block header -%}
 {{ super() }}
 <hr/>
 <script>
   function autoLink(className) {
     var comments = document.querySelectorAll(className);
     for(var i = 0; i < comments.length; i++) {
       comments[i].innerHTML = comments[i].innerHTML.replace(/http:\/\/[^ \t\n<]*/g, '<a href="$&">$&</a>');
@@ skipping 183 matching lines @@
 </center>
 
 </div>
 {% endblock header %}
 
 {% block footer %}
 
 {{ super() }}
 {# <p>Debug info: {{ debuginfo }}</p> #}
 {% endblock %}