This change refactors the npm pkg and npmExecuteScripts implementations
to be reusable for future steps, e.g., npmExecuteLint.
In addition, it fixes few small bugs related to unit test execution on
Windows and the fileUtils mocking implementation.
Co-authored-by: Daniel Kurzynski <daniel.kurzynski@sap.com>
Co-authored-by: Stephan Aßmus <stephan.assmus@sap.com>