Add allow_empty parameter to ImageFolder and related utils

[NicolasHug]

Closes #8297

[pytorch-bot]

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❌ 12 New Failures, 16 Unrelated Failures

As of commit b733bcd with merge base e00f4e6 ():

NEW FAILURES - The following jobs have failed:

• CMake / macos (macos-12) / macos-job (gh)
  The process '/usr/local/bin/git' failed with exit code 128
• CMake / macos (macos-m1-stable) / macos-job (gh)
  The process '/usr/bin/git' failed with exit code 128
• CMake / windows (windows.4xlarge, cpu) / windows-job (gh)
  The process 'C:\Program Files\Git\cmd\git.exe' failed with exit code 128
• Tests / unittests-macos (3.10, macos-12) / macos-job (gh)
  The process '/usr/local/bin/git' failed with exit code 128
• Tests / unittests-macos (3.11, macos-12) / macos-job (gh)
  The process '/usr/local/bin/git' failed with exit code 128
• Tests / unittests-macos (3.8, macos-12) / macos-job (gh)
  The process '/usr/local/bin/git' failed with exit code 128
• Tests / unittests-macos (3.8, macos-m1-stable) / macos-job (gh)
  The process '/usr/bin/git' failed with exit code 128
• Tests / unittests-macos (3.9, macos-12) / macos-job (gh)
  The process '/usr/local/bin/git' failed with exit code 128
• Tests / unittests-windows (3.10, windows.4xlarge, cpu) / windows-job (gh)
  The process 'C:\Program Files\Git\cmd\git.exe' failed with exit code 128
• Tests / unittests-windows (3.11, windows.4xlarge, cpu) / windows-job (gh)
  The process 'C:\Program Files\Git\cmd\git.exe' failed with exit code 128
• Tests / unittests-windows (3.8, windows.4xlarge, cpu) / windows-job (gh)
  The process 'C:\Program Files\Git\cmd\git.exe' failed with exit code 128
• Tests / unittests-windows (3.9, windows.4xlarge, cpu) / windows-job (gh)
  The process 'C:\Program Files\Git\cmd\git.exe' failed with exit code 128

FLAKY - The following jobs failed but were likely due to flakiness present on trunk:

• CMake / linux (linux.12xlarge, cpu) / linux-job (gh)
  The process '/usr/bin/git' failed with exit code 128
• CMake / linux (linux.g5.4xlarge.nvidia.gpu, cuda, 11.8) / linux-job (gh)
  The process '/usr/bin/git' failed with exit code 128
• Docs / build / linux-job (gh)
  The process '/usr/bin/git' failed with exit code 128
• Lint / c-source / linux-job (gh)
  The process '/usr/bin/git' failed with exit code 128
• Lint / python-source-and-configs / linux-job (gh)
  The process '/usr/bin/git' failed with exit code 128
• Lint / python-types / linux-job (gh)
  The process '/usr/bin/git' failed with exit code 128
• Prototype tests on Linux / unittests-prototype (3.8, linux.12xlarge, cpu) / linux-job (gh)
  The process '/usr/bin/git' failed with exit code 128
• Prototype tests on Linux / unittests-prototype (3.8, linux.g5.4xlarge.nvidia.gpu, cuda, 11.8) / linux-job (gh)
  The process '/usr/bin/git' failed with exit code 128
• Prototype tests on Linux / unittests-prototype (3.9, linux.12xlarge, cpu) / linux-job (gh)
  The process '/usr/bin/git' failed with exit code 128
• Tests / onnx / linux-job (gh)
  The process '/usr/bin/git' failed with exit code 128
• Tests / unittests-extended / linux-job (gh)
  The process '/usr/bin/git' failed with exit code 128
• Tests / unittests-linux (3.10, linux.12xlarge, cpu) / linux-job (gh)
  The process '/usr/bin/git' failed with exit code 128
• Tests / unittests-linux (3.11, linux.12xlarge, cpu) / linux-job (gh)
  The process '/usr/bin/git' failed with exit code 128
• Tests / unittests-linux (3.8, linux.12xlarge, cpu) / linux-job (gh)
  The process '/usr/bin/git' failed with exit code 128
• Tests / unittests-linux (3.8, linux.g5.4xlarge.nvidia.gpu, cuda, 11.8) / linux-job (gh)
  The process '/usr/bin/git' failed with exit code 128
• Tests / unittests-linux (3.9, linux.12xlarge, cpu) / linux-job (gh)
  The process '/usr/bin/git' failed with exit code 128

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

[pmeier]

LGTM with one minor comment regarding using the dataset test framework.

[NicolasHug]

linux tests are passing so I'll risk a merge (macos failure is unrelated). Thanks a lot for the review!