[nnc] External functions quantized via Dispatch (#68572)
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/68572
Test Plan: Imported from OSS
Reviewed By: beback4u
Differential Revision: D32522410
Pulled By: IvanKobzarev
fbshipit-source-id: 7bb373819275582bb02e0d2ffd87a78d19f92318
