Constants visibility

Allow filtering constants in Constants::getConstantsValues() by their visibility. It should be possible to filter any combination of public, protected and private (but at least 1 should be passed).

We could possibly use these constants: https://www.php.net/manual/en/class.reflectionclassconstant.php#reflectionclassconstant.constants.modifiers. Also since PHP 8.0 ReflectionClass::getConstants() has parameter filter so once we drop support for PHP 7.4, we could simply use this parameter.