Add operator override for xxhash64, combine_hash internal functions

Summary: TSIA

Differential Revision: D68917161

Author: pradeepvaka

presto-native-execution/presto_cpp/main/types/PrestoToVeloxExpr.cpp

@@ -72,6 +72,8 @@ std::string mapScalarFunction(const std::string& name) {
       {"presto.default.$operator$subscript",
        util::addDefaultNamespacePrefix(
            prestoDefaultNamespacePrefix, "subscript")},
+      {"presto.default.$operator$xx_hash_64", "presto.default.xxhash64_internal"},
+      {"presto.default.combine_hash", "presto.default.combine_hash_internal"},
       // Special form function overrides.
       {"presto.default.in", "in"},
   };