Adding notcheckdeadcode option #719

Job	Run time
cftests-junit on JDK 21	2m 55s
typecheck-part1 on JDK 21	8m 21s
cftests-nonjunit on JDK 21	2m 36s
typecheck-part2 on JDK 21	13m 38s
guava on JDK 21	18m 13s
plume-lib on JDK 21	14m 11s
daikon-part1 on JDK 21	18m 56s
daikon-part2 on JDK 21	15m 26s
jspecify-conformance on JDK 21	3m 25s
jspecify-reference-checker on JDK 21	5m 39s
${{ matrix.script }} on JDK ${{ matrix.java.version }}	0s
${{ matrix.script }} on JDK ${{ matrix.java_version }} on ${{ matrix.os }}	0s
	1h 43m 20s

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