feat(domain): allow duplicated domain names

> fix #432
> I wanted to create a protodomaine : www.zalando.fr/sneakers
> but since www.zalando.fr already exists, Easyadmin blocks me.

migrations/Version20210902124326.php

@@ -0,0 +1,25 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Application\Migrations;
+
+use Doctrine\DBAL\Schema\Schema;
+use Doctrine\Migrations\AbstractMigration;
+
+final class Version20210902124326 extends AbstractMigration
+{
+    public function up(Schema $schema): void
+    {
+        $this->abortIf('mysql' !== $this->connection->getDatabasePlatform()->getName(), 'Migration can only be executed safely on \'mysql\'.');
+
+        $this->addSql('DROP INDEX UNIQ_DOMAIN_NAME ON domain_name');
+    }
+
+    public function down(Schema $schema): void
+    {
+        $this->abortIf('mysql' !== $this->connection->getDatabasePlatform()->getName(), 'Migration can only be executed safely on \'mysql\'.');
+
+        $this->addSql('CREATE UNIQUE INDEX UNIQ_DOMAIN_NAME ON domain_name (name)');
+    }
+}

src/DataFixtures/DomainFixtures.php

@@ -46,6 +46,16 @@ public function load(ObjectManager $manager): void
         $manager->persist($yahoo);
         $this->addReference('yahoo_domain', $yahoo);
 
+        $yahooFr = new DomainName('fr.yahoo.com');
+        $yahooFr->setPath('/');
+        $manager->persist($yahooFr);
+        $this->addReference('com_yahoo_fr', $yahooFr);
+
+        $yahooFrSante = new DomainName('fr.yahoo.com');
+        $yahooFrSante->setPath('/topics/sante-yahoo-france/');
+        $manager->persist($yahooFrSante);
+        $this->addReference('com_yahoo_fr_sante', $yahooFrSante);
+
         $searchEnginesSet = new DomainsSet('Search Engines');
         $searchEnginesSet->addDomain($google);
         $searchEnginesSet->addDomain($bing);

src/Entity/DomainName.php

@@ -35,7 +35,7 @@ class DomainName
     /**
      * @var string
      *
-     * @ORM\Column(name="name", type="string", length=255, nullable=false, unique=true)
+     * @ORM\Column(name="name", type="string", length=255, nullable=false, unique=false)
      * @Assert\Regex("/^(([a-zA-Z0-9]|[a-zA-Z0-9][a-zA-Z0-9\-]*[a-zA-Z0-9])\.)*([A-Za-z0-9]|[A-Za-z0-9][A-Za-z0-9\-]*[A-Za-z0-9])$/")
      */
     private $name;