Deprecate ancient "slowvote.info" API method

Summary: Depends on D20686. Fixes T13350. Now that "slowvote.poll.search" exists, deprecate this old method.

Test Plan: Reviewed method description in Condiut API console in the web UI.

Maniphest Tasks: T13350

Differential Revision: https://secure.phabricator.com/D20687

src/applications/slowvote/conduit/SlowvoteInfoConduitAPIMethod.php

@@ -6,6 +6,14 @@ final class SlowvoteInfoConduitAPIMethod extends SlowvoteConduitAPIMethod {
     return 'slowvote.info';
   }
 
+  public function getMethodStatus() {
+    return self::METHOD_STATUS_DEPRECATED;
+  }
+
+  public function getMethodStatusDescription() {
+    return pht('Replaced by "slowvote.poll.search".');
+  }
+
   public function getMethodDescription() {
     return pht('Retrieve an array of information about a poll.');
   }