American Airlines and other carriers lobbying the Trump administration to limit Qatar Airways’ access to the United States should “shut up and mind their own business,” the Middle Eastern carrier’s chief executive said Monday in the latest of a streak of unpleasantries hurled at his U.S. rivals. CEO Akbar Al Baker also told CNBC on Monday that he continues to seek investments in the United States despite being snubbed when Qatar made a proposal to buy a stake of up to 4.75 percent in Fort…