Revert "Remove some unnecessary <iostream> includes from headers (#106914)"
This reverts commit a6c29b722772816804d54eed070fbb38450d3e6f.
Reverted https://github.com/pytorch/pytorch/pull/106914 on behalf of https://github.com/izaitsevfb due to Causing metal breakage internally, see D48709279 ([comment](https://github.com/pytorch/pytorch/pull/106914#issuecomment-1696670027))
