Back when he was an aspiring musician trying to make it big, John Rzeznik used to make the trek from his house on the East Side to the North Park Theatre on Hertel Avenue.“It was one of the only places in town where you could see an art film, y’know?” he said last week. “So the place means something to me.”But when the lead singer of the Goo Goo Dolls walks inside the theater tonight, it won’t be to see a show. Tonight, he and his band will be the show.In the midst of their intimate, acoustic-themed “Otis Midnight Sessions” tour – which stopped by the Bear’s Den at the Seneca Niagara Casino in