Vice President Kamala Harris kicked off her presidential campaign Monday with a fiery speech at President Joe Biden’s campaign headquarters, where she will carry on her own campaign — and gave a preview of how she’ll take aim at former President Donald Trump on the trail. Harris, who is racking up endorsements including from Biden himself, specifically used her experience as a prosecutor — and contrasted it to Trump’s constant troubles with the law. “As many of you know, before I was elected as vice president, before I was elected as a United States senator, I was the elected attorney general,…