CMake

Update JSON subproject reference and refactor pointer usage for impro… #356

Job	Run time
macos-release	36s
ubuntu-memcheck	58s
ubuntu-address-undefined-coverage	1m 24s
macos-address-undefined	32s
ubuntu-release	55s
windows-debug	1m 31s
windows-release	2m 24s
	8m 20s

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