…`AsTwigTest` to ease extension development (GromNaN)

This PR was squashed before being merged into the 3.x branch.

Discussion
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Create attributes `AsTwigFilter`, `AsTwigFunction` and `AsTwigTest` to ease extension development

One drawback to writing extensions at present is that the declaration of functions/filters/tests is not directly adjacent to the methods. It's worse for runtime extensions because they need to be in 2 different classes. See [`SerializerExtension`](https://github.com/symfony/symfony/blob/7.0/src/Symfony/Bridge/Twig/Extension/SerializerExtension.php) and [`SerializerRuntime`](https://github.com/symfony/symfony/blob/7.0/src/Symfony/Bridge/Twig/Extension/SerializerRuntime.php) as an example.

By using attributes for filters, functions and tests definition, we can make writing extensions more expressive, and use reflection to detect particular options (`needs_environment`, `needs_context`, `is_variadic`).

Example if we implemented the `formatDate` filter: https://github.com/twigphp/Twig/blob/aeeec9a5e907a79e50a6bb78979154599401726e/extra/intl-extra/IntlExtension.php#L392-L395

By using the `AsTwigFilter` attribute, it is not necessary to create the `getFilters()` method. The `needs_environment` option is detected from method signature. The name is still required as the method naming convention (camelCase) doesn't match with Twig naming convention (snake_case).

```php
use Twig\Extension\Attribute\AsTwigFilter;

class IntlExtension
{
    #[AsTwigFilter(name: 'format_date')]
    public function formatDate(Environment $env, $date, ?string $dateFormat = 'medium', string $pattern = '', $timezone = null, string $calendar = 'gregorian', string $locale = null): string
    {
        return $this->formatDateTime($env, $date, $dateFormat, 'none', $pattern, $timezone, $calendar, $locale);
    }
}
```

This approach does not totally replace the current definition of extensions, which is still necessary for advanced needs. It does, however, make for more pleasant reading and writing.

This makes writing lazy-loaded runtime extension the easiest way to create Twig extension in Symfony: symfony/symfony#52748

Related to symfony/symfony#50016

Is there any need to cache the parsing of method attributes? They are only read at compile time, but that can have a performance impact during development or when using dynamic templates.

Commits
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5886907 Create attributes `AsTwigFilter`, `AsTwigFunction` and `AsTwigTest` to ease extension development