[caffe2] Rename c10d::detail::vformat to resolve conflict with fmt (#72039)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/72039
As it turned out calling the function `vformat` was a bad idea because it caused a subtle compilation error due to a conflict with `fmt::vformat` and as a result wrong function overload being found during lookup.
(Note: this ignores all push blocking failures!)
Test Plan:
```
buck build //caffe2:libtorch
```
Reviewed By: cbalioglu
Differential Revision: D33864790
fbshipit-source-id: 08f8a1cdb5dfe72707a00a4ab7a859ea0d33b847
(cherry picked from commit 6fbca57d5e76dea88e1fe60431c5a42ab3ff738b)
