Streamlining guard expect tests (#94404)
Changes:
* Add `simplified` kwarg to let you only render guards that are nontrivial (excludes duck sizing)
* Make a list of strings valid for sources, if you just have some variable names you want to bind to
* Add test helper `show_guards` using these facilities, switch a few tests to it
Signed-off-by: Edward Z. Yang <ezyang@meta.com>
Pull Request resolved: https://github.com/pytorch/pytorch/pull/94404
Approved by: https://github.com/Chillee
