Add AnonymousMigrationsRector

[zingimmick]

Convert migrations to anonymous classes to prevent duplication of class names.
Ref: laravel/framework#36906, laravel/framework#37352

 use Illuminate\Database\Migrations\Migration;

-class CreateUsersTable extends Migration
+return new class extends Migration
 {
     // ...
-}
+};

[zingimmick]

All checks have passed 🎉 @TomasVotruba it is ready for review.

[TomasVotruba]

Thank you 👍
Kudos for docs rebuild!