Intensifying its fight against chronically high inflation, the Federal Reserve raised its key interest rate Wednesday by a substantial three-quarters of a point for a third straight time, an aggressive pace that is heightening the risk of an eventual recession. The Fed’s move boosted its benchmark short-term rate, which affects many consumer and business loans, to a range of 3% to 3.25%, the highest level since early 2008. The policymakers also signaled that by early 2023, they expect to have further raised rates much higher than they had projected in June.