Add Listener\ Initializable interface

[alanbem]

interface Initializable
{
     public function initialize(): void;
}

class OrdersProjector implements Listener, Listener\Initializable
{
	
     public function initialize(): void
     {
          // for example create database table, during first run
     }
}

The method initialize would be run only once when subscription starts to process first event. It should not run after reset