[operator_compile_check] Add FakeTensor testing (#103595)
This PR adds dedicated FakeTensor testing to operator_compile_check. We
reuse CrossRefFakeMode to do this and improve the error messages on it.
Note that this only really runs detailed tests for operators that do not
have data-dependent output shape. In the future we should add something
like a dynamic CrossRefFakeMode.
Test Plan:
- existing tests (these now have improved error messages).
Pull Request resolved: https://github.com/pytorch/pytorch/pull/103595
Approved by: https://github.com/ezyang, https://github.com/soulitzer
