use irange for loops (#70248)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/70248
Modified loops in files under fbsource/fbcode/caffe2/ from the format
```
for(TYPE var=x0;var<x_max;x++)
```
to the format
```
for(const auto var: irange(xmax))
```
This was achieved by running r-barnes's loop upgrader script (D28874212) with some modification to exclude all files under /torch/jit and a number of reversions or unused variable suppression warnings added by hand.
Test Plan: Sandcastle
Reviewed By: malfet
Differential Revision: D32813863
fbshipit-source-id: 527244b4a2b220fdfe7f17dee3599603f492a2ca
