refactor(@angular/cli): introduce new package manager abstraction #2033

Job	Run time
build-e2e-windows	17s
lint	2m 18s
build	20s
e2e-windows	0s
publish-snapshots	-1s
test	-1s
Browser Compatibility Tests	-1s
e2e-package-managers	0s
e2e	0s
e2e-snapshots	0s
	2m 52s

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