Fix nn.Module type hints

[adamjstewart]

All of these inputs are classes, not instances.

[HuggingFaceDocBuilderDev]

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[rwightman]

@adamjstewart started fixing some of those but never finished... I have a LayerType .... LayerType = Union[str, Callable, Type[torch.nn.Module]] that is meant to cover layer types, usually at the main model level, or major block level that is intended to pass through a module type, creation fn, or string to pass to a factory. Should any of the ones changed in this PR be a LayerType or are they appropriately scoped as Type[nn.Module] ?

[adamjstewart]

There is an existing bug here. act_layer and conv_layer both default to None, but None is an invalid input and will cause the code to crash. Should we change the default and make it non-optional?

[adamjstewart]

None of these are valid LayerTypes because they don't support strings, they must be callables.

Note that I found one typing bug that could have been caught by mypy if you were using it.