Massachusetts has struck a multi-billion dollar deal with the federal government that Gov. Deval Patrick says will help the state move ahead with plans to overhaul the way it pays for health care coverage. Patrick praised the three-year, $26.7 billion Medicaid waiver — a $5.7 billion increase over the previous waiver. Patrick said the money will help the state preserve existing eligibility and benefit levels in Medicaid and Commonwealth Care programs. Commonwealth Care is the subsidized insurance program established by the state’s landmark 2006 health care law.