refactor(@angular/cli): extract update migration logic into separate … #2664

Job	Run time
list	20s
workflow (build-cli)	1m 43s
workflow (modules-builder-tests)	1m 48s
workflow (devkit-core-tests)	1m 29s
workflow (devkit-core-tests-rerun)	1m 29s
workflow (build-unit-tests)	2m 28s
	9m 17s

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