Added REPORT_STEPS: to the GEN_DATA configuration

This PR adds a required REPORT_STEPS:xxx attribute to the GEN_DATA configuration. By forcing the user to specify for which report step(s) the GEN_DATA vector is active it easier to quality check the loading of results, and the normal load-failure path can be followed.

In addition to the actual REPORT_STEPS:xxx requirement the patch contains much refactoring to better enable testing.