Put symint overloads on a different name

Due to implicit conversion shenanigans, having both IntArrayRef
and SymIntArrayRef overloads makes {} ambiguous.  While we could
fix this by making a single unified type that accepts all the overloads
we want, an easier fix was to just push the SymIntArrayRef overload
to its own name.

Signed-off-by: Edward Z. Yang <ezyangfb.com>

Pull Request resolved: https://github.com/pytorch/pytorch/pull/79281

Approved by: https://github.com/suo

torchgen/model.py

@@ -1225,6 +1225,10 @@ class FunctionSchema:
     def is_functional_fn(self) -> bool:
         return "functional" in self.name.overload_name
 
+    def is_symint_fn(self) -> bool:
+        # TODO: make this more robust
+        return "SymInt" in self.name.overload_name
+
     def is_out_fn(self) -> bool:
         # Note [is_out_fn]
         #