[jit] Make `ModuleList`s a sugared value (#34320)
Summary:
Previously when emitting subscripts we only emitted actual values, but
now they may sometimes emit a `ModuleValue`, so it should stay as a
`SugaredValue`. This allows for the result of the subscript to be
treated as a real module (i.e. you can just do `self.modlist[1](inputs)`
instead of `self.modlist[1].forward(inputs)`)
Pull Request resolved: https://github.com/pytorch/pytorch/pull/34320
Pulled By: driazati
Differential Revision: D20345642
fbshipit-source-id: 2bedf9a454af747b704422f6bbb8370cbdf4bf61
