[BC Break] Remove conflicting expression language custom functions

[ogizanagi]

with new 6.1 operators: https://symfony.com/blog/new-in-symfony-6-1-improved-expressionlanguage-syntax

especially the contains one which currently conflicts with the operator and produces an exception:

Symfony\Component\ExpressionLanguage\SyntaxError: Unexpected token "operator" of value "contains" around position 1 for expression contains(article.slug, "foo").

For projects that'll still want to use these function, until installing Symfony 6.1, they can extend the expression language by registering a custom expression provider tagged with stenope.expression_language_provider:

class ExpressionLanguageProvider implements ExpressionFunctionProviderInterface
{
    public function getFunctions(): iterable
    {
        yield from [
            ExpressionFunction::fromPhp('str_contains', 'contains'),
            ExpressionFunction::fromPhp('str_starts_with', 'starts_with'),
            ExpressionFunction::fromPhp('str_ends_with', 'ends_with'),
        ];
    }
}

[ogizanagi]

Replaced by #143