validator: introduce experimental node:validator module #5919

Job	Run time
Build slim tarball	2m 11s
aarch64-darwin: with shared libraries	19m 5s
x86_64-linux: with shared libraries	26m 24s
aarch64-linux: with shared libraries	21m 54s
x86_64-darwin: with shared libraries	34m 33s
	1h 44m 7s

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