message: Fix MTL::LinkedFunctions bug in metal-cpp.h
  MTLLinkedFunctions groups is an NS::Dictionary* not an NS::Array*
  ie.
  nonatomic, copy, nullable) NSDictionary<NSString *,NSArray<id<MTLFunction>> *> *groups;
diff: @@ -16167,8 +16167,8 @@ public:
  NS::Array* binaryFunctions() const;
  void setBinaryFunctions(const NS::Array* binaryFunctions);
  - NS::Array* groups() const;
  - void setGroups(const NS::Array* groups);
  + NS::Dictionary* groups() const;
  + void setGroups(const NS::Dictionary* groups);
  NS::Array* privateFunctions() const;
  void setPrivateFunctions(const NS::Array* privateFunctions);
  @@ -16211,12 +16211,12 @@ _MTL_INLINE void MTL::LinkedFunctions::setBinaryFunctions(const NS::Array* binar
  Object::sendMessage<void>(this, _MTL_PRIVATE_SEL(setBinaryFunctions_), binaryFunctions);
  }
  -_MTL_INLINE NS::Array* MTL::LinkedFunctions::groups() const
  +_MTL_INLINE NS::Dictionary* MTL::LinkedFunctions::groups() const
  {
  - return Object::sendMessage<NS::Array*>(this, _MTL_PRIVATE_SEL(groups));
  + return Object::sendMessage<NS::Dictionary*>(this, _MTL_PRIVATE_SEL(groups));
  }
  -_MTL_INLINE void MTL::LinkedFunctions::setGroups(const NS::Array* groups)
  +_MTL_INLINE void MTL::LinkedFunctions::setGroups(const NS::Dictionary* groups)
  {
  Object::sendMessage<void>(this, _MTL_PRIVATE_SEL(setGroups_), groups);
  }
  