example of updating dim order for specific part of graph (#4404)

Summary:
Pull Request resolved: https://github.com/pytorch/executorch/pull/4404

An example of how to update the tensor's memory format of specific part in graph by inserting `_to_dim_order_copy` op before and after the specific part we want to update (here is the mul op).

Making it as a test for memory format pass.

Reviewed By: digantdesai, larryliu0820

Differential Revision: D60200604

fbshipit-source-id: 1dc88e0b84ba085a1fbcfe52b142ba6a014c2673