Make `compare_results()` import path public (#5225)

Summary:
Pull Request resolved: https://github.com/pytorch/executorch/pull/5225

`compare_results()` is a util function that is used outside of the inspector tool itself. We will also probably mention it in PTC as a public util function. This diff makes it "public" aka removes the underscore prefix in the import paths.

Reviewed By: dbort

Differential Revision: D62450959

fbshipit-source-id: 5688a79001b76c2e99ac76a9238828c6031f7291