aten_unfold needed for Whisper

[abock]

We need to implement aten_unfold, possibly the other variants as this will come up when exporting Whisper through the Dynamo exporter.

cc @kunal-vaishnavi, @thiagocrepaldi, @justinchuby

[BowenBao]

Surprised whisper is not part of torchbench.

@MaanavD might be good practice contributing this model to torchbench, as material for your tutorial.

[MaanavD]

@BowenBao Yep, actually that's the second request I've had for Whisper in Torchbench, I will look into it shortly!