If Saturday Night Live Season 45 has had one sweet spot lately, it's making light of Joker. NBC's hit late-night series struck gold once again on Saturday's most recent episode with a sketch called "Grouch", featuring host David Harbour playing the titular role of Oscar the Grouch in a trailer promising to explore the dark origins of the iconic Sesame Street character. The entire "Grouch" sketch is framed as a trailer, the first of many smart moves for this bit. Harbour plays Oscar, a garbage man living in New York City who is so disillusioned with …