.count-only/.bool-only exist on combinations/permutations subs, but not methods

[zoffixznet]

Filing for records. Looking at the code, should be possible for both forms to have these optimizations.

<Zoffix_> m: .iterator.^lookup('count-only').so.say for permutations(1), combinations(1,1), 1.permutations, 1.combinations(1)
<evalable6> Zoffix_, rakudo-moar 8943f7c54: OUTPUT: «True␤True␤False␤False␤»
<Zoffix_> m: .iterator.^lookup('bool-only').so.say for permutations(1), combinations(1,1), 1.permutations, 1.combinations(1)
<evalable6> Zoffix_, rakudo-moar 8943f7c54: OUTPUT: «True␤True␤False␤False␤»

[zoffixznet]

Did the List.permutations one in d4f53ed5d9 with tests in 19604c2d21 Not yet sure what a good approach for List.combinations would look like, if anyone got ideas.