Move generateDiffusionURI() into PhabricatorRepository

Summary: Ref T4245. This further reduces the reliance on callsigns in Diffusion.

Test Plan:
  - Pretty reasonable test coverage already exists.
  - Browsed repository list, browse view, history view, content view, change view, commit view, tag view, branch view of repositories.

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T4245

Differential Revision: https://secure.phabricator.com/D14937

src/applications/repository/query/PhabricatorRepositorySearchEngine.php

@@ -175,9 +175,8 @@ final class PhabricatorRepositorySearchEngine
 
       $size = $repository->getCommitCount();
       if ($size) {
-        $history_uri = DiffusionRequest::generateDiffusionURI(
+        $history_uri = $repository->generateURI(
           array(
-            'repository' => $repository,
             'action' => 'history',
           ));