Make datapipe.py compatible with torchdata==0.11 or later

[drivanov]

With torch 2.7/torchdata 0.11 releases, the datapype.py example fails

python3 /workspace/examples/datapipe.py 
Traceback (most recent call last):
  File "/workspace/examples/datapipe.py", line 17, in <module>
    from torchdata.datapipes.iter import FileLister, FileOpener, IterDataPipe
ModuleNotFoundError: No module named 'torchdata.datapipes'

fails because some classes have been moved from torchdata to torch nd a few methods, including in_memory_cache, have been removed.

The current PR resolves this issue in that example.

NOTES:
Running this example with the option --task mesh was failing even with previous versions of torch/torchdata packages

• because 3991 out of 7981 are binary, not text files in the required "OFF" format;
• if the meshio and torch_claster packages are not installed.

Proposed changes address both these issues.