Migrate torch.export from TorchScript for PyTorch model export

[mshr-h]

TorchScript is no longer active development, and it's recommended to migrate to torch.export based model export.

TODOs:

• Migrate PyTorch model exporter to torch.export method.

refs:

• Introduction to TorchScript — PyTorch Tutorials 2.6.0+cu124 documentation
• torch.export — PyTorch 2.6 documentation