Add syntactic support for asymmetric visibility

[thekid]

This pull request adds syntactic support for asymmetric visibility using (set) specifiers on property modifiers. The modifiers contain the string as declared, e.g. "private(set)" in the below example and need to be translated by the compiler!

Example

Support in property declarations:

class Person {
  public private(set) string $name= 'Test';
}
 
$person= new Person();
echo $person->name;       // OK
$person->name= 'Changed'; // Visibility error

Support in promoted constructor parameters:

class Person {
  public function __construct(private(set) string $name) { }
}

See https://wiki.php.net/rfc/asymmetric-visibility-v2 and xp-framework/compiler#182

[thekid]

Released in https://github.com/xp-framework/ast/releases/tag/v11.3.0