HfO<sub>2</sub>–Al<sub>2</sub>O<sub>3</sub> Dielectric Layer for a Performing Metal–Ferroelectric–Insulator–Semiconductor Structure with a Ferroelectric 0.5Ba(Zr<sub>0.2</sub>Ti<sub>0.8</sub>)O<sub>3</sub>-0.5(Ba<sub>0.7</sub>Ca<sub>0.3</sub>)TiO<sub>3</sub> Thin Film