IndexSelect constraints, add a missing constraint in constraint tranformations and modify tests accordingly (#81344)
- Constraints for IndexSelect, which allow us to replace a dimension from the input
- There was a bug, which is that for a constraint of the form "x \leq 4" where x is a tensor, we did not generate the constraint" x = Dyn in the transformation step. This is fixed and the tests are modified accordingly.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/81344
Approved by: https://github.com/jansel, https://github.com/jamesr66a
