make utils support empty dim order (#2142)

Summary:
Pull Request resolved: https://github.com/pytorch/executorch/pull/2142
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This update makes util function support empty dim order, to make the empty dim order behave the same as empty memory format (preserve_format)

Reviewed By: digantdesai, larryliu0820

Differential Revision: D54236386

fbshipit-source-id: 21f5076b203a27f31e6eee7ba44d547f763bbd04