At first blush, Carter Smith, the oldest character in Kimberly Belflower’s new play, “John Proctor is the Villain,” is the kind of high school English teacher you only wish you’d had. Played by Gabriel Ebert, a Tony Award-winning actor who has often downplayed his lanky good looks, Mr. Smith engages the students in his junior-year honors class with both contagious enthusiasm and empathy, encouraging self-expression and mutual respect while easily enforcing discipline.