[Composable API] Add fully_shard debug function to print sharded tree structure, module names and managed param fqns (#99133)
Adding a fully_shard debug function to print sharded tree structure like following format, return module names and their managed parameter fqns as well.
![Screenshot 2023-04-18 at 5 14 54 PM](https://user-images.githubusercontent.com/48731194/232931628-169a63a9-b4d5-4902-9cfd-f40113f3ec98.png)
Pull Request resolved: https://github.com/pytorch/pytorch/pull/99133
Approved by: https://github.com/rohan-varma