Add unit tests for OutputHelper class #739

Job	Run time
copyright	3m 14s
shellcheck	3m 5s
checkstyle	3m 26s
build	5m 11s
spotbugs	5m 26s
cli/linux-amd64	4m 53s
tests/cli-linux	4m 52s
cli/windows-amd64	5m 32s
javadoc	4m 7s
tests/cli-functional-linux	6m 35s
vscode-ext	3m 58s
tests/archetype-linux	4m 41s
cli/darwin-amd64	5m 53s
tests/linker-linux	4m 36s
tests/others-linux	5m 50s
tests/cli-windows	6m 5s
tests/cli-functional-windows	7m 33s
tests/archetype-windows	5m 27s
tests/linker-windows	5m 41s
tests/others-windows	7m 26s
cli/binaries	6s
tests/results	3s
gate	1s
	1h 43m 41s

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