Fix mobile type resolution in unpickling (#37425)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/37425
The mobile type resolver that we inject into the unpickler currently
creates a dummy type for everything, even built-in types like
List[int]. This PR restricts that behavior to types that start with
`__torch__`, and uses the mobile type parser for everything else.
I don't like this solution because it relies on a fragile invariant that
all "class-like" types have qualified names that start with `__torch__`.
I think the long term solution is to just re-use the script type parser
here.
Test Plan: Imported from OSS
Differential Revision: D21291331
Pulled By: suo
fbshipit-source-id: c94709bcbd1bac75336e033fd9d3afa6656b0a77
