[NNC] channels last propagation within NNC fusion group (#76948)
Decide the memory layout propagation policy and propagate it within the NNC fusion group. The memory layout propagation policy could be `Contiguous` and `Channels-last contiguous`.
- `Contiguous`: Convert the non-contiguous including channels-last contiguous input tensors to contiguous and generate the contiguous output `Buf` for lowering function.
- `Channels-last contiguous`: Convert the input tensors to channels-last contiguous and generate the channels-last contiguous output `Buf` for lowering function.
Currently, the rule is simple. If all the input and out tensors of the NNC fusion group are channels-last contiguous, then the propagated memory layout is `Channels-last contiguous`. Otherwise, it is always `Contiguous` which is as same as current situation. It means that this PR provides a fast path to channels-last and the optimization is conservative since its trigger conditions are strict.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/76948
Approved by: https://github.com/ZolotukhinM
