[JIT] Handle modules that already have __constants__ (#60003)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/60003
**Summary**
`infer_concrete_type_builder` in `_recursive.py` assumes `__constants__`
is a `set` if it exists as an attribute on the module being scripted.
Instead, it should create a set out of whatever `__constants__` is.
**Test Plan**
Ran code from the issue.
**Fixes**
This commit fixes #59947.
Test Plan: Imported from OSS
Reviewed By: pbelevich
Differential Revision: D29174243
Pulled By: SplitInfinity
fbshipit-source-id: aeb8bded80038da35478714b6a697a766ac447f5
