[easy][PyTorchEdge] print error message when failing to load model file (#63404)

[easy][PyTorchEdge] print error message when failing to load model file (#63404)

Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/63404

# Context
Loading a model file using `fopen` might error out for multiple reasons. Repro'ing the error on devices takes some time and efforts. Logging the error no# will help in debugging and fixing the error quickly.

# Mitigation
Printout the error message of the `fopen` to help users debug the issue.

Test Plan:
```
(base) [pavithran@devvm1803.vll0 /data/users/pavithran/fbsource] buck run xplat/caffe2/fb/lite_predictor:lite_predictor -- --model=/home/pavithran/models/prod/GAaNhAoTIV6cIvgJAHn30m8NR1QgbmQwAAAA.ptl --use_bundled_input=0
Building: finished in 0.5 sec (100%) 354/354 jobs, 0/354 updated
  Total time: 0.6 sec
Run with 24 threads
Run with 24 threads
Loading model...
terminate called after throwing an instance of 'c10::Error'
  what():  open file failed because of errno 2 on fopen: No such file or directory, file path: /home/pavithran/models/prod/GAaNhAoTIV6cIvgJAHn30m8NR1QgbmQwAAAA.ptl
Exception raised from RAIIFile at xplat/caffe2/caffe2/serialize/file_adapter.cc:15 (most recent call first):
(no backtrace available)
```

Reviewed By: dhruvbird

Differential Revision: D30372308

fbshipit-source-id: 5346e828f53f6bc5d871b403586566a3332a389a