Add torch.do_assert, which is symbolically traceable (#45188)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/45188
This is a symbolically traceable alternative to Python's `assert`.
It should be useful to allow people who want to use FX to also
be able to assert things.
A bunch of TODO(before) land are inline - would love thoughts
on where is the best place for this code to live, and what this
function should be called (since `assert` is reserved).
Test Plan:
```
python test/test_fx.py TestFX.test_symbolic_trace_assert
```
Imported from OSS
Reviewed By: jamesr66a
Differential Revision: D23861567
fbshipit-source-id: d9d6b9556140faccc0290eba1fabea401d7850de
