Datepicker: Unescape double escaped ids when handling events. Fixes #8480 - Datepicker 1.8.22 escaped id does not work.

(cherry picked from commit 30b579f)

Author: scottgonzalez

ui/jquery.ui.datepicker.js

@@ -1408,7 +1408,7 @@ $.extend(Datepicker.prototype, {
 	 */
 	_attachHandlers: function(inst) {
 		var stepMonths = this._get(inst, 'stepMonths');
-		var id = '#' + inst.id;
+		var id = '#' + inst.id.replace( /\\\\/g, "\\" );
 		inst.dpDiv.find('[data-handler]').map(function () {
 			var handler = {
 				prev: function () {