Type annotations for util.data. (#18963)

Summary:
I haven't had a chance to rigorously try these out yet so don't merge yet.
Closes #18725.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/18963

Differential Revision: D14832897

Pulled By: ezyang

fbshipit-source-id: 4780e7a34126bc66ddbfd9d808dfc9e0edd77e68

setup.py

@@ -735,6 +735,7 @@ if __name__ == '__main__':
                 'cuda/*.pyi',
                 'optim/*.pyi',
                 'autograd/*.pyi',
+                'utils/data/*.pyi',
                 'lib/*.so*',
                 'lib/*.dylib*',
                 'lib/*.dll',