New Order for New York's G.O.P. and Democrats
Article discusses effect Repr Charles E Schumer's victory in Senate race over Sen Alfonse D'Amato will have on New York State politics; Senator Alfonse M D'Amato, who has long reigned as undisputed king of New York's Republican Party, will turn over that title to Gov George Pataki, who swept to re-election over Democrat Peter F Vallone; Representative Charles E Schumer, by virtue of his defeat of D'Amato, will be expected by many state Democrats to head party; photo (M)