record_function: update to use custom_class API (#76420)
Re-submit of gh-72302
This still has a small performance hit, but it much smaller. On my
machine I see `_record_fucntion_exit._RecordFunction` takes 1.05 us
compared to the `Tensor` overload taking 0.79 us.
In an overall comparison, I see a 0.7 us slowdown from 6.0 us to
6.7 us for this timeit benchmark
```python
import torch
def foo():
with torch.profiler.record_function("foo"):
return torch.eye(3)
%timeit foo()
```
Pull Request resolved: https://github.com/pytorch/pytorch/pull/76420
Approved by: https://github.com/robieta
