[Symfony 7.3] Merge AsTwigFilter/AsTwigFunction rules into single rule, add getTests() support

[TomasVotruba]

GetFiltersToAsTwigFilterAttributeRector and GetFunctionsToAsTwigFunctionAttributeRector could never convert a class that declares both getFilters() and getFunctions().

Each rule checks stillRequiresAbstractExtension() before converting - and the sibling method is exactly such a blocker. So the filter rule bailed because getFunctions() was still there, and the function rule bailed because getFilters() was still there. Very common shape in real Twig extensions.

This merges both into GetFiltersAndFunctionsToAsTwigAttributeRector, which collects conversions of getFilters(), getFunctions() and getTests() in one pass, validates them all, and only then removes extends AbstractExtension.

Also adds getTests() -> #[AsTwigTest], with per-method option mapping (#[AsTwigTest] has no isSafe/preservesSafety/preEscape).

Before

final class FormatterExtension extends AbstractExtension
{
    public function getFilters(): array
    {
        return [
            new TwigFilter('simple_array_to_html', $this->simpleArrayToHtml(...), ['is_safe' => ['html']]),
        ];
    }

    public function getFunctions(): array
    {
        return [
            new TwigFunction('normalize_string_value', $this->normalizeStringValue(...)),
            new TwigFunction('simple_array_to_html', $this->simpleArrayToHtml(...), ['is_safe' => ['html']]),
        ];
    }

    public function normalizeStringValue(string $value): string
    {
        return $value;
    }

    public function simpleArrayToHtml(array $values): string
    {
        return implode('<br />', $values);
    }
}

After

final class FormatterExtension
{
    #[AsTwigFunction(name: 'normalize_string_value')]
    public function normalizeStringValue(string $value): string
    {
        return $value;
    }

    #[AsTwigFilter(name: 'simple_array_to_html', isSafe: ['html'])]
    #[AsTwigFunction(name: 'simple_array_to_html', isSafe: ['html'])]
    public function simpleArrayToHtml(array $values): string
    {
        return implode('<br />', $values);
    }
}

Both old rules are removed and replaced in the twig/twig 3.21 composer-based set; their fixtures are merged into the new rule test.

Skip behaviour is unchanged: if any present get*() method cannot be fully converted (closures, injected-service callables, built-in name overrides, GlobalsInterface, token parsers, ...), the whole class is left alone, since extends AbstractExtension must stay.