By Howard Schneider and Ann Saphir (Reuters) – Federal Reserve Chair Jerome Powell has often pointed to the months before the pandemic as a heyday for the U.S. economy, and he is counting on an across-the-board return to economic conditions circa 2019 to help win a fight against high inflation without sparking higher unemployment. It is a calculated gamble the world economy will emerge from the pandemic, a war in eastern Europe, and a potential reshuffling of global supply lines and still largely operate as it did before, without any permanent change in price and wage dynamics. When pressed on…