Fix transpose of empty initializers called from constant folding

[xadupre]

Description

ConstantFolding crashes when a constant empty initializer is transposed.

Motivation and Context

This rare case happened when converting a LLM into onnx with static shape.

[Copilot]

Pull Request Overview

This PR fixes a crash in ConstantFolding when attempting to transpose constant empty initializers by adding a guard condition to skip the transpose operation for empty tensors.

• Added guard condition to skip transpose operation when tensor size is 0
• Added test case to verify the fix works correctly for empty initializer transpose scenarios

Reviewed Changes

Copilot reviewed 2 out of 3 changed files in this pull request and generated 1 comment.

File	Description
onnxruntime/test/optimizer/graph_transform_test.cc	Adds test case to verify constant folding doesn't crash on empty initializer transpose
onnxruntime/core/optimizer/transpose_optimization/ort_optimizer_api_impl.cc	Adds size check guard to prevent transpose operation on empty tensors

---

_{Tip: Customize your code reviews with copilot-instructions.md. Create the file or learn how to get started.}