[FSDP] Include module classes in `ModuleWrapPolicy.__repr__` (#89058)
Before:
```
<torch.distributed.fsdp.wrap.ModuleWrapPolicy object at 0x7fd4280f0fd0>
```
After:
```
<torch.distributed.fsdp.wrap.ModuleWrapPolicy object at 0x7fd4280f0fd0>({<class 'transformers.models.t5.modeling_t5.T5Block'>})
```
Pull Request resolved: https://github.com/pytorch/pytorch/pull/89058
Approved by: https://github.com/mrshenli
