Add unit tests for OutputHelper class #735

Job	Run time
checkstyle	3m 21s
build	4m 56s
copyright	3m 13s
shellcheck	3m 7s
spotbugs	5m 17s
cli/linux-amd64	4m 35s
javadoc	4m 5s
cli/windows-amd64	5m 36s
tests/cli-linux	4m 14s
cli/darwin-amd64	5m 49s
vscode-ext	3m 52s
tests/cli-functional-linux	4m 13s
tests/archetype-linux	4m 14s
tests/linker-linux	4m 14s
tests/others-linux	4m 14s
tests/cli-windows	3m 52s
tests/cli-functional-windows	4m 11s
tests/archetype-windows	4m 11s
tests/linker-windows	4m 10s
tests/others-windows	4m 9s
cli/binaries	7s
tests/results	0s
gate	0s
	1h 25m 40s

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