Add peephole for len(x.size()) (#59051)
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/59051
Test Plan: Imported from OSS
Reviewed By: Krovatkin
Differential Revision: D28727247
Pulled By: eellison
fbshipit-source-id: 6474d39773b640992bdaf261575a3dbd48c6d56c
