Add the ability to save events in the write model Feature class

[kpicaza]

Epic: pheature-flags/pheature-flags#297

We have to store the actions that occurred in the Pheature\Core\Toggle\Write\Feature as events.

Example implementation, of what we are thinking on:

<?php
...
class Feature {
   private array $events = [];

   public function popEvents()
   {
       $events = $this-events;
       foreach($events as $event) {
            $this->apply($event); // not mandatory because we are not doing event sourcing here
       }
       $this->events = [];
       return $events;
   }
}