Give QuantHashes proper .of / keyof methods

So that hyper methods may actually properly recognize them.

Note that properly parameterizing Associative gave rise to all sort of weird
errors during the building of the setting.  Which is why the local overrides.

src/core/Baggy.pm6

@@ -12,6 +12,8 @@ my role Baggy does QuantHash {
 # Immutables aspects of Bag/Mix, need to live to Bag/Mix respectively.
 
 #--- interface methods
+    method of() { UInt }
+
     multi method ACCEPTS(Baggy:U: \other --> Bool:D) {
         other.^does(self)
     }

src/core/Mixy.pm6

@@ -1,5 +1,7 @@
 my role Mixy does Baggy  {
 
+    method of() { Real }
+
     multi method hash(Mixy:D: --> Hash:D) { self!HASHIFY(Real) }
     multi method Hash(Mixy:D: --> Hash:D) { self!HASHIFY(Any) }
 

src/core/QuantHash.pm6

@@ -1,5 +1,7 @@
 my role QuantHash does Associative {
 
+    method keyof() { Any }
+
     method SET-SELF(QuantHash:D: \elems) {  # cannot be a private method
         nqp::stmts(
           nqp::if(

src/core/Setty.pm6

@@ -1,6 +1,8 @@
 my role Setty does QuantHash {
     has Rakudo::Internals::IterationSet $!elems; # key.WHICH => key
 
+    method of() { Bool }
+
     # helper sub to create Set from iterator, check for laziness
     sub create-from-iterator(\type, \iterator --> Setty:D) {
         nqp::if(