make MapHigherOrder create map_impl (#1388)

Summary:
Pull Request resolved: https://github.com/pytorch/executorch/pull/1388

This is a reland of https://github.com/pytorch/pytorch/issues/115205, which gets reverted due to internal test failure.

X-link: https://github.com/pytorch/pytorch/pull/115561

Reviewed By: angelayi

Differential Revision: D52040993

Pulled By: ydwu4

fbshipit-source-id: c5b9bc0d1af78cca355bec36334e5bec0cf93d61