Support preserving calling convention to some modules.

Summary:
X-link: https://github.com/pytorch/pytorch/pull/106798

APS use this feature to swap out some submodules after unflattening.

Reviewed By: kit1980, tugsbayasgalan

Differential Revision: D48154341

fbshipit-source-id: 687393582596d679a51f236ae1665a5e07cdaadc