PORTLAND, Ore. — Momentum is building in a case regarding homeless encampments that will be argued before the U.S. Supreme Court next month and could have major implications for cities as homelessness nationwide has reached record highs.Dozens of briefs have been filed in recent days, including from the Department of Justice, members of Congress and state attorneys general. They joined the growing number of western state and local officials who have submitted briefs urging the justices to overturn a controversial …