Add the rest of the `dict` API (#21979)
Summary:
This adds the rest of the `dict.???` methods that were missing
Pull Request resolved: https://github.com/pytorch/pytorch/pull/21979
Pulled By: driazati
Differential Revision: D15999938
fbshipit-source-id: 7bc2a55e3f791015a0ff2e3731703075cf0770ee
