chore: use array instead of Vec in keccak256 #14677

Job	Run time
build-noirc-abi	2m 20s
build-nargo	2m 18s
build-acvm-js	2m 2s
build-noir-wasm	4m 32s
ACVM JS (Browser)	1m 20s
ACVM JS (Node.js)	41s
Example scripts	17s
Check external repo - ${{ matrix.project.repo }}	0s
noirc_abi	1m 16s
noir_codegen	1m 13s
Noir JS	1m 6s
Integration Tests (Node)	2m 26s
Integration Tests (Browser)	2m 5s
noir_wasm	1m 56s
End	1s
	23m 33s

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