added scan method into FakeRedisMasterFactory

Taken from commits into 4.x branch

df083c8
a5c9235

Required for PROVIDER-284

Infrastructure/Persistence/Redis/FakeRedisMasterFactory.php

@@ -23,6 +23,12 @@ public function lPush($key, ...$value1) { return false; }
             public function rPush($key, ...$value1) { return false; }
 
             public function blPop($key, $timeout_or_key, ...$extra_args) { return []; }
+
+            public function scan(&$iterator, $pattern = null, $count = 0)
+            {
+                $iterator = 0;
+                return ['something'];
+            }
         };
 
         return new $fakeRedis;