Fixing "naive" `forward` of `ModuleList` and `ModuleDict (#48785)
Summary:
**Goal:** Making sure "calling"/"forwarding" a `ModuleList` or `ModuleDict` produce the intended `NotImpmentedError`.
**Current behavior:**
Currently, when naively calling `forward` user ends up with the confusing error message:
```python
TypeError: forward() takes 1 positional argument but 2 were given
```
Instead of the intended `NotImplementedError.`
This minor issue was brought up by vadimkantorov in issue https://github.com/pytorch/pytorch/issues/37718 [here][1], also by a confused stackoverflow user [here][2].
**What this PR includes:**
Remove `forward` altogether from `ModuleList` and `ModuleDict` to fall back on the `_forward_unimplemented` of `Module` that properly throws `NotImplementedError` regardless of input arguments.
Appropriate test was added to `test_nn.py`
Fixes previous PR https://github.com/pytorch/pytorch/issues/48698 and PR https://github.com/pytorch/pytorch/issues/48783 (third time's a charm? I'm really sorry for the mess)
Test added according to ngimel [request][3].
[1]: https://github.com/pytorch/pytorch/issues/37718#issuecomment-736333345
[2]: https://stackoverflow.com/q/65096679/1714410
[3]: https://github.com/pytorch/pytorch/pull/48698#issuecomment-737398693
Pull Request resolved: https://github.com/pytorch/pytorch/pull/48785
Reviewed By: zhangguanheng66
Differential Revision: D25359759
Pulled By: jbschlosser
fbshipit-source-id: 28f82386f2e9a2a9b0b0b81b16dba6b79398bd34
