feat(perf): Track last loads per block in mem2reg and remove them if possible #15691

Job	Run time
build-acvm-js	1m 39s
build-nargo	2m 35s
build-noirc-abi	1m 44s
build-noir-wasm	3m 43s
ACVM JS (Node.js)	39s
ACVM JS (Browser)	1m 18s
noirc_abi	1m 42s
Example scripts	10s
noir_codegen	1m 5s
Noir JS	1m 13s
Check external repo - ${{ matrix.project.repo }}	0s
Integration Tests (Browser)	2m 8s
noir_wasm	1m 54s
Integration Tests (Node)	2m 23s
End	1s
	22m 14s

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