Add option to export phi-3-mini model via buck2

as title

Differential Revision: [D59500806](https://our.internmc.facebook.com/intern/diff/D59500806/)

ghstack-source-id: 233088629
Pull Request resolved: #4189

Author: helunwencser

examples/models/phi-3-mini/export_model.py renamed to examples/models/phi-3-mini/export_phi-3-mini.py

@@ -19,7 +19,6 @@
     get_symmetric_quantization_config,
     XNNPACKQuantizer,
 )
-from torch.export import export
 
 from transformers import Phi3ForCausalLM
 
@@ -48,8 +47,14 @@ def main() -> None:
         model(*example_inputs)
         model = convert_pt2e(model, fold_quantize=False)
         DuplicateDynamicQuantChainPass()(model)
-        model = export(
-            model, example_inputs, dynamic_shapes=dynamic_shape, strict=False
+        # TODO(lunwenh): update it to use export once
+        # https://github.com/pytorch/pytorch/issues/128394 is resolved.
+        model = torch.export._trace._export(
+            model,
+            example_inputs,
+            dynamic_shapes=dynamic_shape,
+            strict=False,
+            pre_dispatch=False,
         )
 
     edge_config = get_xnnpack_edge_compile_config()

examples/models/phi-3-mini/targets.bzl

@@ -0,0 +1,8 @@
+def define_common_targets():
+    """
+    Defines targets that should be shared between fbcode and xplat.
+
+    The directory containing this targets.bzl file should also contain both
+    TARGETS and BUCK files that call this function.
+    """
+    pass