Remove shape testing code from dialects edge (#607)

Summary:
Pull Request resolved: https://github.com/pytorch/executorch/pull/607

The purpose of this diff stack is to clean up the OpInput code that lives inside exir/dialects/edge, leaving only what is needed to search allowed dtypes per op.
Code that is only used for test generation is removed from exir/dialects/edge

Reviewed By: larryliu0820

Differential Revision: D49891113

fbshipit-source-id: b77906ae04143d94a6799f35c1408252ed2b2c8a