feat: "in memory" behavior

[nikophil]

This PR introduces "in-memory" behavior

fixes #533

It makes integration testing with "in memory" repositories very easy!

Here is the proposal:
Given some kind of DDD or hexagonal architecture, repositories in domain are usually interfaces, which main implementation is a Doctrine one. "in memory" version of these repositories will exist and would be injected in the container in test environment.

This PR exposes a new interface Zenstruck\Foundry\InMemory\InMemoryRepository, e.g.:

/**
 * @implements InMemoryRepository<Address>
 */
final class InMemoryAddressRepository implements InMemoryRepository, DomainAddressRepository
{
    /** @use InMemoryRepositoryTrait<Address> */
    use InMemoryRepositoryTrait;

    public static function _class(): string
    {
        return Address::class;
    }

    // + all methods implementing "DomainAddressRepository"
}

It also exposes a new attribute #[AsInMemoryTest], which will disable persistence of the factories, and register an "after instantiate" hook, which will store the objects in their respective "in memory" repositories:

#[AsInMemoryTest]
class SomeTest extends KernelTestCase
{
    private InMemoryAddressRepository $addressRepository;
 
    protected function setUp(): void
    {
        $this->addressRepository = self::getContainer()->get(InMemoryAddressRepository::class);
    }

    #[Test]
    public function object_should_be_accessible_from_in_memory_repository(): void
    {
        $address = AddressFactory::createOne();

        self::assertSame([$address], $this->addressRepository->_all());
    }
}

A GenericInMemoryRepository is also added for convenience, when the given in memory repository is missing.