refactor and move createException function (#29605)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/29605
Adds a wrapper around the existing createException function that
allows passing of an error string, instead of a regular C++ exception. This
allows us to createExceptions for errors that aren't necessarilu c++
exceptions. This function is used by
https://github.com/pytorch/pytorch/pull/29601 and
https://github.com/pytorch/pytorch/pull/26336.
ghstack-source-id: 93819039
Test Plan: Unit tests pass
Differential Revision: D18439216
fbshipit-source-id: 70b6a2e4f107304e322cdd2630847ad0071bc0c1
