feat: `std::hint::black_box` function. #15632

Job	Run time
build-nargo	2m 26s
build-noirc-abi	1m 34s
build-acvm-js	1m 24s
build-noir-wasm	3m 46s
noirc_abi	1m 27s
ACVM JS (Browser)	1m 20s
ACVM JS (Node.js)	40s
Noir JS	1m 2s
noir_codegen	1m 13s
Example scripts	10s
Check external repo - ${{ matrix.project.repo }}	0s
Integration Tests (Node)	2m 30s
noir_wasm	1m 46s
Integration Tests (Browser)	2m 4s
End	1s
	21m 23s

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