Simplify searching in Advanced Search.

This pull request addresses the problem where objects cannot be searched against Contact before they are refreshed from the server.  Previously Contact, Owner, and search term in Advanced Search were handled with a custom filter, which does not allow for deferred processing (i.e. waiting until instances have been refreshed).  Instead, these are now handled with a Search list loader, which uses the server side search API to find objects matching the search term and the contact_id param.<br><br>Ref b/17130617