fix(@angular/build): emit a warning when `outputHashing` is set to `a… #1441

Job	Run time
list	24s
workflow (devkit-core-tests-rerun)	1m 14s
workflow (build-unit-tests)	2m 4s
workflow (modules-builder-tests)	1m 35s
workflow (devkit-core-tests)	1m 12s
workflow (build-cli)	1m 24s
	7m 53s

Provide feedback