Centralise `echoerr` function #844

Job	Run time
Prepare environment	6s
jdks / get-supported-jdks	1s
Build with default JDK	2m 50s
Build with jdk-17	2m 52s
Build with jdk-21	2m 59s
Test pushing image (dry run) / prepare	2s
Test pushing image (dry run) / jdks / get-supported-jdks	1s
Test pushing image (dry run) / push (17, slim)	1m 36s
Test pushing image (dry run) / push (17)	2m 7s
Test pushing image (dry run) / push (21, slim)	1m 37s
Test pushing image (dry run) / push (21)	2m 29s
	16m 40s

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