TorchDynamo: weight prepack for onednn convolution external call (#88988)
This PR is about enabled weight prepack using the MKLDNN tensor:
1. enable fake tensor mode for MKLDNN tensor input.
2. make convolution fusion kernel support MKLDNN tensor input.
3. do the weight prepack at FX fusion step.
For better performance, we always use channels_last for CPU convolution path. because we test that the channels_last path can get a better performance than block input path, and also avoid the activation's layout conversion(plain to block, block to plain), currently, there only need plain to plain format conversion.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/88988
Approved by: https://github.com/jgong5, https://github.com/jansel
