feat(mail-test): implement email testing functionality

- Created MailTestController to handle email sending requests.
- Added SendTestMailRequest for validating email input.
- Developed MailTestService to manage email sending logic.
- Introduced TestMail Mailable for formatting test emails.
- Defined API route for sending test emails.
- Created EmailIntegrationSeeder to seed email integration settings.
- Updated DatabaseSeeder to include EmailIntegrationSeeder.
- Added MailTestControllerTest to ensure email sending functionality works as expected.

database/seeders/DatabaseSeeder.php

@@ -30,6 +30,7 @@ class DatabaseSeeder extends Seeder
             ProductCatalogFromImagesSeeder::class,
             FiestaFutbolInfantilProductSeeder::class,
             TelepagosIntegrationSeeder::class,
+            EmailIntegrationSeeder::class,
             MenuSeeder::class,
         ]);
     }