[NNC] Add utility functions to check channels-last contiguous (#75938)
Summary:
The `Buf` uses `std::vector<ExprHandle>` to represent its strides. The `ExprHandle` could be an immediate value or a mathematical expression with variables involved both for the static shape and dynamic shape. So it is hard to directly deduce the channels-last contiguous layout based on the numerical calculation. Hence, the utility functions of this PR are based on the pattern match to check whether the `Buf` is channels-last contiguous.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/75938
Reviewed By: cpuhrsch
Differential Revision: D35724091
Pulled By: ZolotukhinM
fbshipit-source-id: f79ae21749d0aad8601f0434b52df88602ff09bf
(cherry picked from commit 3712bbbe4bea57c5c1abe1eafde4b8778e13e0c4)
