Add SelectionDataset, refactor ShuffledDataset, and add transform tests. #8492

Job	Run time
prepare-checks	2s
documentation (stable)	4m 24s
code-quality (stable)	3m 3s
linux-std-wgpu-tests (stable)	8m 13s
linux-std-tests (prev)	9m 8s
linux-std-tests (stable)	9m 8s
linux-std-cuda-tests (stable)	8m 13s
windows-std-tests (stable)	8m 56s
linux-no-std-tests (stable)	6m 3s
linux-no-std-tests (prev)	5m 21s
linux-std-vulkan-tests (stable)	7m 57s
	1h 10m 28s

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