Adding ModuleList to modules.h (#25346)
Summary:
Here is a PR adding ```ModuleList``` to ```modules.h``` so that it can be used by including ```torch/torch.h```.
yf225 edit: Closes https://github.com/pytorch/pytorch/issues/25293.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/25346
Differential Revision: D17115013
Pulled By: yf225
fbshipit-source-id: 38a1848b9a8272fa411865dfc83b76d10c5789a0
