fix: add support for descending sorting of full text search (#7496)

src/RestQuery.js

@@ -143,7 +143,7 @@ function RestQuery(
         var fields = restOptions.order.split(',');
         this.findOptions.sort = fields.reduce((sortMap, field) => {
           field = field.trim();
-          if (field === '$score') {
+          if (field === '$score' || field === '-$score') {
             sortMap.score = { $meta: 'textScore' };
           } else if (field[0] == '-') {
             sortMap[field.slice(1)] = -1;