Print restart attempt as part of Dynamo log context (#108864)
Now looks like:
```
[2023-09-08 06:04:48,532] [0/0] torch._dynamo.symbolic_convert: [DEBUG] TRACE STORE_ATTR foo [ConstantVariable(int), NNModule
Variable()]
[2023-09-08 06:04:48,532] [0/0] torch._dynamo.convert_frame: [INFO]
Restarting analysis due to _dynamo/variables/nn_module.py
:138 in convert_to_unspecialized
[2023-09-08 06:04:48,533] [0/0_1] torch._dynamo.symbolic_convert: [INFO] Step 1: torchdynamo start tracing f /data/users/ezyang/c/pytorch/a.py:6
[2023-09-08 06:04:48,533] [0/0_1] torch._dynamo.symbolic_convert.__trace_source: [DEBUG] TRACE starts_line f /data/users/ezyang/c/pytorch/a.py:6
```
I'm happy to bikeshed the exact formatting of the attempt number if you
want.
Signed-off-by: Edward Z. Yang <ezyang@meta.com>
Pull Request resolved: https://github.com/pytorch/pytorch/pull/108864
Approved by: https://github.com/mlazos, https://github.com/voznesenskym
