Creating Keys in PIR

[chromatic]

I'm writing tests for namespaces now (and fixing code), and testing the keyed 
variants is a real pain, mostly because creating nested Key PMCs in PIR is so 
face-stabbingly awful, if it's even possible.

Without hard-coding the names, I'd love to see working PIR for creating a key 
which can refer to the namespace [ 'A'; 'Nested'; 'Namespace' ].

Yes, that implies an interface like:

        .local pmc some_key
        some_key = create_nested_key( 'A', 'Nested', 'Namespace' )

Anyone?

-- c