LibJS: Implement Set.prototype.symmetricDifference

Author: https://github.com/IdanHo
Commit: e359eeabe8
Pull-request: https://github.com/SerenityOS/serenity/pull/16279
Reviewed-by: https://github.com/TobyAsE
Reviewed-by: https://github.com/davidot ✅
Reviewed-by: https://github.com/linusg ✅

Userland/Libraries/LibJS/Runtime/CommonPropertyNames.h

@@ -488,6 +488,7 @@ namespace JS {
     P(sup)                                   \
     P(supportedLocalesOf)                    \
     P(supportedValuesOf)                     \
+    P(symmetricDifference)                   \
     P(tan)                                   \
     P(tanh)                                  \
     P(test)                                  \