Add namedtuple return for min, median, mode, kthvalue, add test for namedtuple return API (#16186)
Summary:
This partially fixes https://github.com/pytorch/pytorch/issues/394 and depend on https://github.com/pytorch/pytorch/pull/15429. I suggest to review this only after https://github.com/pytorch/pytorch/pull/15429 get landed, otherwise the diff might be large to review.
The test only allows explicitly whitelisted operators to have named return.
Differential Revision: D14070735
Pulled By: ezyang
fbshipit-source-id: ace2a672998b4e4a8094f52cbda5aa1cea6e3b42
