WASHINGTON — President Joe Biden is moving swiftly to dismantle Donald Trump’s legacy on his first day in office, signing a series of executive actions that reverse course on immigration, climate change, racial equity and the handling of the coronavirus pandemic.The new president signed the orders just hours after taking the oath of office at the Capitol, pivoting quickly from his pared-down inauguration ceremony to enacting his agenda. With the stroke of a pen, Biden ordered a halt to the construction of Trump …