Fix typing error of torch/nn/modules/container.pyi.in (#33686)
Summary:
* `Sequential` has `__iter__` method, but type stub doesn't
* `ModuleList.__getitem__` returns `Module`, but type stub doesn't
* Type stub says `ParameterList` has `insert` method, but actual `ParameterList` doesn't
* `ParameterDict.__getitem__` should returns `Parameter`
* `ParameterList` and `ParameterDict` have `extra_repr` methods
---
torch/nn/modules/container.py: https://github.com/pytorch/pytorch/blob/master/torch/nn/modules/container.py
torch/nn/modules/container.pyi.in: https://github.com/pytorch/pytorch/blob/master/torch/nn/modules/container.pyi.in
Pull Request resolved: https://github.com/pytorch/pytorch/pull/33686
Differential Revision: D20086730
Pulled By: ngimel
fbshipit-source-id: a8271489417461c67ff84a239c4cd96c3aa17b5c
