add tests that schemas are valid (#30749)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/30749
Add check to schemas that the schema is sane.
I removed the defaults from symbolic_script because they were in some cases wrong and don't actually do anything. At the point they're invoked the forward should already have matched all arguments.
Test Plan: Imported from OSS
Differential Revision: D18864775
Pulled By: eellison
fbshipit-source-id: 273d7e96d65b8a3d3de72e2d7bfcdf2417046c6b
