SYDNEY (Reuters) – The Americans are coming. And the Japanese and Europeans. Australia is being invaded by a swathe of foreign retailers, piling pressure on a local industry already battered by weak consumer spending and ruthless internet competition. U.S. retail giant Williams-Sonoma Inc opens its first owner-operated stores outside of North America in Sydney early next year. Japan's Uniqlo and U.S. youth label Hollister are also scheduled to debut here in 2013, while womenswear store Zara , Britain's youth label Topshop and U.S. …