State Senate leaders have unveiled a wide-ranging health care reform proposal that sets goals of lowering costs and providing residents access to first-rate care regardless of income or geography.The more than 100-page bill was filed on Tuesday amid continued uncertainty over the future of federal health care policy that could have dramatic consequences for Massachusetts.The proposal from Senate Democrats on Beacon Hill aims to squeeze out as much as $525 million in overall health care savings by 2020.Provisions include reducing prescription drug costs and the number of unnecessary hospital emergency room visits, and narrowing the wide gap in payments between community hospitals and their large Boston counterparts.It also includes some, but not all provisions of Republican Gov. Charlie Baker's plan to lower state Medicaid costs.