President Joe Biden came out swinging at his campaign rally in Detroit, Michigan, on Friday, armed with a volley of zingers against former President Donald Trump, self-deprecating jokes about his own age, a laundry list of his policy accomplishments and plans for a second term, and unabashed defiance against the punditry and members of his own party who have spent weeks raising doubts about his ability to stay in the race. It was exactly the performance many commenters on social media, including some who had been wavering since his shaky debate with Trump in Atlanta, had been hoping for — and …