Doctrine extensions for PHPStan

DQL validation for parse errors, unknown entity classes and unknown persistent fields. QueryBuilder validation is also supported. Recognizes magic findBy*, findOneBy* and countBy* methods on EntityRepository. Validates entity fields in repository findBy, findBy, findOneBy, findOneBy, count and countBy method calls. Interprets EntityRepository MyEntity correctly in phpDocs for further type inference of methods called on the repository. Provides correct return for Doctrine\ORM\EntityManager::getRepository(). Provides correct return type for Doctrine\ORM\EntityManager::find, getReference and getPartialReference when Foo::class entity class name is provided as the first argument. Queries are analyzed statically and do not require a running database server. This makes use of the Doctrine DQL parser and entities metadata.