Opinion on removing name dependency from Class__::isAnonymous()

[tscni]

Hi

This has been brought up before partially (#554).
PHPStan gives anonymous class nodes a name to generalize behavior between anonymous and regular classes.
As pointed out before, this does of course break PhpParser\Node\Stmt\Class_::isAnonymous().

We can resolve this by extending Class_ and overriding the method to always return true. (as implemented here phpstan/phpstan-src#3343), but it feels a bit cumbersome to do.

So here I'm mainly wondering what your opinion is on changing Class_::isAnoynmous() to use e.g. a new "is anonymous" flag or similar.