[Search] Searching on embeds causes InvalidArgumentException

[KDederichs]

Describe the bug
If you have an associated entity with an embed and you're trying to configure search for it you'll get an InvalidArgumentException.

To Reproduce

Have entity Foo contain a ManyToOne reference to Bar.
Bar has a property customerAddress that is an embed.

Try to configure Foos search like this:

    public function configureCrud(Crud $crud): Crud
    {
        return $crud
            ->setSearchFields(['bar.customerAddress.firstName']);
    }

(OPTIONAL) Additional context

Looks like we need some logic there to check if the thing you're trying to search is an association or an embed.

InvalidArgumentException:
Association name expected, 'customerAddress' is not an association.

  at vendor/doctrine/orm/src/Mapping/ClassMetadata.php:2521
  at Doctrine\ORM\Mapping\ClassMetadata->getAssociationTargetClass('customerAddress')
     (vendor/easycorp/easyadmin-bundle/src/Orm/EntityRepository.php:290)
  at EasyCorp\Bundle\EasyAdminBundle\Orm\EntityRepository->getSearchablePropertiesConfig(object(QueryBuilder), object(SearchDto), object(EntityDto))
     (vendor/easycorp/easyadmin-bundle/src/Orm/EntityRepository.php:76)
  at EasyCorp\Bundle\EasyAdminBundle\Orm\EntityRepository->addSearchClause(object(QueryBuilder), object(SearchDto), object(EntityDto), 'Doctrine\\DBAL\\Platforms\\PostgreSQL120Platform')
     (vendor/easycorp/easyadmin-bundle/src/Orm/EntityRepository.php:60)
  at EasyCorp\Bundle\EasyAdminBundle\Orm\EntityRepository->createQueryBuilder(object(SearchDto), object(EntityDto), object(FieldCollection), object(FilterCollection))
     (vendor/easycorp/easyadmin-bundle/src/Controller/AbstractCrudController.php:495)
  at EasyCorp\Bundle\EasyAdminBundle\Controller\AbstractCrudController->createIndexQueryBuilder(object(SearchDto), object(EntityDto), object(FieldCollection), object(FilterCollection))
     (vendor/easycorp/easyadmin-bundle/src/Controller/AbstractCrudController.php:137)
  at EasyCorp\Bundle\EasyAdminBundle\Controller\AbstractCrudController->index(object(AdminContext))
     (vendor/symfony/http-kernel/HttpKernel.php:183)
  at Symfony\Component\HttpKernel\HttpKernel->handleRaw(object(Request), 1)
     (vendor/symfony/http-kernel/HttpKernel.php:76)
  at Symfony\Component\HttpKernel\HttpKernel->handle(object(Request), 1, true)
     (vendor/symfony/http-kernel/Kernel.php:193)
  at Symfony\Component\HttpKernel\Kernel->handle(object(Request))
     (vendor/symfony/runtime/Runner/Symfony/HttpKernelRunner.php:35)
  at Symfony\Component\Runtime\Runner\Symfony\HttpKernelRunner->run()
     (vendor/autoload_runtime.php:32)
  at require_once('/app/vendor/autoload_runtime.php')
     (public/index.php:5)