Welcome back to Tune In: our weekly newsletter offering a guide to the best of the week's TV. Each week, Variety's TV team combs through the week's schedule, selecting our picks of what to watch and when/how to watch them. This week, a whole string of shows premiere their final seasons, including Netflix's animated comedy “BoJack Horseman” and NBC's revival of “Will & Grace.” “Catherine the Great,” HBO, Monday, 10 p.m. Helen Mirren dons yet another crown, this time that of 18th century Russian empress Catherine the Great. The premiere of this HBO-Sky limited series collaboration sees Catherine both fighting to retain power after usurping her husband Peter III, and looking for love. “Castle Rock,”