CMake

Cleanup/refactor of decoders and related tests #3161

Job	Run time
linux (linux.12xlarge, cpu) / linux-job	53s
linux (linux.g5.4xlarge.nvidia.gpu, cuda, 11.8) / linux-job	53s
macos (macos-m1-stable) / macos-job	1m 11s
windows (windows.4xlarge, cpu) / windows-job	2m 14s
windows (windows.g5.4xlarge.nvidia.gpu, cuda, 11.8) / windows-job	11m 49s
	17m 0s

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