NEW YORK — The Legal Aid Society is gearing up to file a lawsuit in coming weeks seeking to force City Hall to implement a legislative package that would expand access to a rental voucher program that helps low-income New Yorkers afford permanent housing. The City Council package — which Mayor Adams opposes because he says the chamber passed it without identifying a funding stream — consists of several bills designed to overhaul the so-called CityFHEPS voucher program. Chief among the reforms is a measure that would abolish a rule requiring low-income New Yorkers to enter a city shelter before…