existing folder match for a path E.g. if \a path is "/home/user/projects/2018/P4343" and "/home/user/projects" exists but no "2018" subfolder exists, then the function will return "/home/user/projects". (Suprisingly no existing Qt method for this!)
Use Qt style "returns .." tense instead of "return ..", and lock this in with a documentation compliance unit test
