Design, Synthesis, and Biological Evaluation of 1‐[(Biarylmethyl)methylamino]‐2‐(2,4‐difluorophenyl)‐3‐(1H‐1,2,4‐triazol‐1‐yl)propan‐2‐ols as Potent Antifungal Agents: New Insights into Structure–Activity Relationships