By David Gaffen NEW YORK (Reuters) -Oil prices strengthened on Wednesday after European Union leaders agreed to a phased ban on Russian oil and as China ended its COVID-19 lockdown in Shanghai, which could bolster demand in an already tight market. Oil benchmarks have marched steadily higher for several weeks as Russian shipments are squeezed by EU and U.S. sanctions and as India and China can only buy so much from Russia, the world’s largest exporter of crude and fuel. Brent crude was up $1.83, or 1.6%, at $117.46 a barrel at 11:56 a.m. EDT (1556 GMT). U.S. West Texas Intermediate crude gaine…