Kellyanne Conway, a former adviser to Donald Trump, trashes the ex-president’s son-in-law Jared Kushner as a “shrewd and calculating” power-hungry backstabber in a new White House memoir. Conway pulls no punches regarding Ivanka Trump’s husband, saying he was a master of White House office politics who constantly sought to add to his portfolio without accepting any accountability. “There was no subject he considered beyond his expertise. If Martian attacks had come across the radar, he would have happily added them to his ever-bulging portfolio,” she writes. “He’d have made sure you knew he’d …