Add `skuba migrate` command to upgrade projects to Node.js 20 #9004

Job	Run time
Lint & Test	1m 39s
Integrate (express-rest-api)	1m 2s
Integrate (greeter)	56s
Integrate (koa-rest-api)	1m 9s
Integrate (lambda-sqs-worker)	1m 22s
Integrate (lambda-sqs-worker-cdk)	1m 4s
Integrate (oss-npm-package)	1m 6s
Integrate (private-npm-package)	1m 1s
	9m 19s

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