Enable constant methods in cadence export. (pytorch#7948)

Summary:

Add option to specify constant methods in export. The constants show up as methods (similar to "forward") in the serialized .pte.

Reviewed By: zonglinpeng

Differential Revision: D68637824

Author: hsharma35

backends/cadence/aot/compiler.py

@@ -174,6 +174,7 @@ def export_to_edge(
     model: torch.nn.Module,
     inputs: tuple[object, ...],
     dump_graphs: bool = False,
+    constant_methods: Optional[dict[str, object]] = None,
 ) -> EdgeProgramManager:
     assert isinstance(model, torch.nn.Module), "model should be an nn.Module"
 
@@ -195,6 +196,7 @@ def export_to_edge(
                 torch.ops.aten.angle.default,
             ],
         ),
+        constant_methods=constant_methods,
     )
 
     if dump_graphs: