Thanks for your posting. While there’s currently no explicit support for this, you can implement something similar with the structured steps control and maybe custom test statuses (e.g. “Skipped” or similar for irrelevant steps). The steps control looks as follows:
Custom statuses can be configured under Administration > Customiziations > Statuses (the table with the colors).
You can freely skip individual steps on the Add Test Result dialog (by leaving them Untested or setting them to Skipped) and still set the overall status for the test to Passed (or Failed/something else). Would this work for you?