By Luc Cohen NEW YORK (Reuters) -Tom Barrack, a onetime fundraiser for Donald Trump, acknowledged under cross-examination on Thursday that he hoped his ties to the then-president would encourage a United Arab Emirates official to invest with his company, but said he did not agree to exchange political access for a business relationship. Federal prosecutors in Brooklyn say Barrack, 75, used his influence with Trump’s campaign and administration in 2016 and 2017 to promote the United Arab Emirates’ interests without informing the U.S. attorney general he was acting as an agent of the country, as…