StoreGate: Update CondHandleKey::initialize() to match VarHandleKey().
Add a bool argument to CondHandleKey::initialize(), and also add an overload taking AllowEmptyEnum. This matches the current declarations in the VarHandleKey base class.
Add a bool argument to CondHandleKey::initialize(), and also add an overload taking AllowEmptyEnum. This matches the current declarations in the VarHandleKey base class.