Jack Eichel fondly remembers sitting with his dad in the TD Garden stands, watching his favorite hockey players. The 22-year-old from nearby North Chelmsford was the star attraction Sunday night, and he didn’t disappoint. Eichel had two goals and two assists, including the primary helper on Jeff Skinner’s winning goal with 3:13 remaining, to lead the Buffalo Sabres past the Boston Bruins 4-2. “I just picture myself in the crowd watching guys that I loved watching when I was a kid,” Eichel said.