By Richard Cowan and David Morgan WASHINGTON (Reuters) -U.S. congressional negotiators on Monday were nearing a deal on a bill to provide Ukraine with billions of dollars in emergency aid, as well as fund the U.S. government through Sept. 30 and provide money to address COVID-19. Lawmakers were racing against a midnight Friday deadline for passing such a sweeping bill, before existing funds are exhausted. Failure to meet the deadline would either require another stop-gap funding bill or force partial government shutdowns during a time of international crisis. Congressional sources with knowled…