[cudnn] Support v8 API in fbcode (#96512)
Summary: It turns out we never turn on cudnn v8 API which blocks bf16 conv. Enable the new v8 API
Test Plan: buck run mode/dev-nosan scripts/xdwang/example:fc_pytorch
Reviewed By: ngimel
Differential Revision: D43784279
Pull Request resolved: https://github.com/pytorch/pytorch/pull/96512
Approved by: https://github.com/malfet
