chore: add a span to track timing of brillig gen #11482

Job	Run time
build-nargo	2m 37s
build-noirc-abi	1m 26s
build-noir-wasm	4m 8s
build-acvm-js	1m 21s
ACVM JS (Node.js)	36s
ACVM JS (Browser)	1m 38s
noirc_abi	1m 36s
Check external repo - zac-williamson/noir-edwards	5s
Example scripts	20s
noir_codegen	58s
Noir JS	1m 21s
Integration Tests (Browser)	3m 49s
Integration Tests (Node)	2m 20s
noir_wasm	2m 31s
End	1s
	24m 47s

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