Adding Support for Doctrine ORM

Doctrine, a widely-used object-relational mapping library in PHP, has now been integrated with a new ORM library specifically designed for it, allowing seamless integration with various applications, including those not built on the Symfony framework. The library enables activity tracking by hooking into the entity lifecycle events, such as creation and deletion, using a ModelListener class that interacts with Stream's API to manage activity feeds. An example application demonstrates the integration by allowing users to sign up, follow others, and interact through posts and likes, with activities being monitored and displayed in personalized feeds. The library requires activity entities to implement a specific interface or use a provided trait to ensure compatibility, facilitating the generation of activity data for Stream's services. Users can perform advanced operations using the FeedManager to manage timelines and activity streams efficiently. The integration aims to simplify the process of building scalable news feeds and activity streams, inviting feedback and collaboration from the community for enhancements.