LONDON--The United Kingdom's newest class of aircraft carrier, the HMS Queen Elizabeth, will host United States F-35s starting in 2021, U.K. Defense Secretary Michael Fallon said Wednesday.The Queen Elizabeth-class carriers will be the biggest and most powerful warships ever constructed for Royal Navy, according to the U.K. Ministry of Defence. The other Queen Elizabeth-class carrier will be the HMS Prince of Wales, which had its final structural section lowered into place earlier this summer, according to the Royal Navy. The…