CMake

add gdown as optional requirement for dataset GDrive download #2009

Job	Run time
linux (linux.12xlarge, cpu) / linux-job	3m 39s
linux (linux.g5.4xlarge.nvidia.gpu, cuda, 11.8) / linux-job	9m 8s
macos (macos-12) / macos-job	10m 21s
macos (macos-m1-stable) / macos-job	2m 44s
windows (windows.4xlarge, cpu) / windows-job	21m 32s
windows (windows.g5.4xlarge.nvidia.gpu, cuda, 11.8) / windows-job	30m 13s
	1h 17m 37s

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