feat: add AsDbalType attribute

[syl20b]

Description

This PR add a new AsDbalType attribute to automatically register the related class as a DBAL type.

Problem Solved

Currently, to register a custom DBAL type, it must be manually declared in the Doctrine configuration file:

# config/packages/doctrine.yaml

doctrine:
    dbal:
        types:
            my_custom_type: App\Type\MyCustomType

This approach is verbose and requires the developer to manage configuration in addition to the type class itself.

Feature Added

The addition of the #[AsDbalType] attribute allows the application to automatically detect and register any class that uses this attribute.

---

Concrete Usage Example

Here is how you can register a custom type directly via the attribute, without touching the YAML configuration:

1. Creating the Custom Type

<?php

namespace App\Type;

use Doctrine\DBAL\Types\Type;
use Doctrine\DBAL\Platforms\AbstractPlatform;
use Doctrine\Bundle\DoctrineBundle\Attribute\AsDoctrineType;

#[AsDbalType(name: 'my_custom_type')]
final class MyCustomType extends Type
{
    // ... implementation of methods
}

2. Usage in an Entity

You can then use this type directly in your entities:

<?php

namespace App\Entity;

use Doctrine\ORM\Mapping as ORM;

class Product
{
    #[ORM\Column(type: 'my_custom_type', length: 255)]
    private ?string $name = null;
    
    // ...
}

Advantages

• Zero Configuration: No need to modify doctrine.yaml for every new custom type.
• Discoverability: The DBAL type and its name are declared in the same location as its implementation.

[syl20b]

@stof is it ok for you?