[Relay][Pass] Update SimplifyTranspose to correctly simplify rank changing layout transforms

[csullivan]

This PR adds support to SimplifyTranspose to simplify consecutive transpose<->layout_transform operations when the layout transform involves a rank expansion or contraction. The added unit test fails on main because the current SimplifyTranspose only doesn't consider the case when the layout transform and transpose may act on tensors of different rank. As an example,

NCHW4c -> LayoutTransform -> NCHW -> Transpose -> NHWC

now simplifies to

NCHW4c -> LayoutTransform -> NHWC.

The reverse, rank expansion, is also supported.

[csullivan]

cc @comaniac @ANSHUMAN87 @mbrookhart

[comaniac]

Thanks for the fix! Overall LGTM. Please add more comments to help future maintaners catch up the logic easily.

[ANSHUMAN87]

Thanks @csullivan for the PR!
Please find some comments.
Overall LGTM!

[csullivan]

Thanks @comaniac @ANSHUMAN87! I've extended the support for various rank changing layout transform + transpose patterns. Please see the additional tests for an overview and let me know other change requests you may have.

[comaniac]

LGTM. One bonus suggestion is it would be great to have one comment on the top of each new added test cases to brief explain what's testing.

[mbrookhart]

@csullivan Thanks for the contribution. What's the status on this? I looks like it has a lint error.

[ANSHUMAN87]

Looks great now! 👍

[comaniac]

Thanks @csullivan @ANSHUMAN87