Give nqp named anon methods

[Kaiepi]

Allows for the following pattern:

nqp::getstaticcode(
    anon method introspective() {
        nqp::die('nice callstack!')
    });

Which would be very useful in Rakudo's bootstrapping, for instance. Many of Rakudo's core methods lack names on their code objects, which tends to be rather confusing for newcomers introspecting methods.

Unsure of how to add a test for this.

[Kaiepi]

This should demonstrate that this behaves:

class WithNamedAnon {
    method named_anon() {
        nqp::getstaticcode(anon method named_anon() { })
    }
}

my &named_anon := WithNamedAnon.named_anon();
say(nqp::getcodename(&named_anon) eq 'named_anon');
say(!(named_anon(WithNamedAnon) =:= &named_anon));