feats: add loader in classification task datasets.

[GdoongMathew]

Related to #8922 & #8762

1. Add loader argument in classification datasets.
2. Update the transform part of the docstring, to notify users that the transform image may in PIL.Image type or torch.Tensor type, based on the provided loader.
3. Enable SUPPORT_TV_IMAGE_DECODE unittests.

[pytorch-bot]

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❌ 6 New Failures, 1 Unrelated Failure

As of commit d1be85b with merge base 86f8eb0 ():

NEW FAILURES - The following jobs have failed:

• Lint / bc (gh)
  Process completed with exit code 1.
• Tests / unittests-linux (3.10, linux.12xlarge, cpu) / linux-job (gh)
  RuntimeError: Command docker exec -t 993884290e6ef0bc48b8e12dccf0faf15ec7845df1af52fce2dc344faf0675b1 /exec failed with exit code 1
• Tests / unittests-linux (3.11, linux.12xlarge, cpu) / linux-job (gh)
  RuntimeError: Command docker exec -t e1f709be8266a37c9dc4819a1ea53de2e133b64c58cbe9bbbc35650a38c55422 /exec failed with exit code 1
• Tests / unittests-linux (3.12, linux.12xlarge, cpu) / linux-job (gh)
  RuntimeError: Command docker exec -t 39f17111173825a7ea2d54d5401719f9ecc59889c45a5e0a7316203784a452f9 /exec failed with exit code 1
• Tests / unittests-linux (3.9, linux.12xlarge, cpu) / linux-job (gh)
  RuntimeError: Command docker exec -t 4a51bf3d568b944d22128f2f4be00ddb96fede99337d0478bdb0320f45a0fe2f /exec failed with exit code 1
• Tests / unittests-macos (3.12, macos-m1-stable) / macos-job (gh)
  RuntimeError: Command bash /Users/ec2-user/runner/_work/_temp/exec_script failed with exit code 1

BROKEN TRUNK - The following job failed but were present on the merge base:

👉 Rebase onto the `viable/strict` branch to avoid these failures

• Tests / unittests-windows (3.9, windows.g5.4xlarge.nvidia.gpu, cuda, 11.8) / windows-job (gh) (trunk failure)
  AttributeError: '_OpNamespace' 'image' object has no attribute '_jpeg_version'

This comment was automatically generated by Dr. CI and updates every 15 minutes.

[NicolasHug]

Thanks a lot for the PR @GdoongMathew . There just seem tob e some minor type annotations issues,, I think we just need to add pathlib.Path as an accepted input type. Do you mind taking a look? Otherwise this looks great!

  torchvision/datasets/sun397.py:65: error: Argument 1 has incompatible type
  "Path"; expected "str"  [arg-type]
              image = self.loader(image_file)
                                  ^~~~~~~~~~
  torchvision/datasets/food101.py:79: error: Argument 1 has incompatible type
  "Path"; expected "str"  [arg-type]
              image = self.loader(image_file)
                                  ^~~~~~~~~~
  torchvision/datasets/flowers102.py:87: error: Argument 1 has incompatible type
  "Path"; expected "str"  [arg-type]
              image = self.loader(image_file)
                                  ^~~~~~~~~~
  torchvision/datasets/dtd.py:86: error: Argument 1 has incompatible type "Path";
  expected "str"  [arg-type]
              image = self.loader(image_file)
                                  ^~~~~~~~~~
  torchvision/datasets/clevr.py:73: error: Argument 1 has incompatible type
  "Path"; expected "str"  [arg-type]
              image = self.loader(image_file)
                                  ^~~~~~~~~~
  Found 5 errors in 5 files (checked 235 source files)

[GdoongMathew]

Hi @NicolasHug, I've updated the type annotation.
Thanks~

[NicolasHug]

Thanks a lot @GdoongMathew !