chore: allow setting namespace visibility on functions #4806

Job	Run time
build-noirc-abi	2m 20s
build-nargo	2m 26s
build-noir-wasm	2m 23s
build-acvm-js	2m 21s
noirc_abi	53s
noir-js-backend-barretenberg	41s
ACVM JS (Browser)	1m 9s
ACVM JS (Node.js)	36s
noir_codegen	56s
Noir JS	1m 20s
Integration Tests (Node)	3m 39s
noir_wasm	1m 9s
Integration Tests (Browser)	5m 15s
End	1s
	25m 9s

Provide feedback