Use .tabular_sort instead of .stable_sort_by

`.stable_sort_by` was deprecated here:

ManageIQ/more_core_extensions#76

And will be removed in `more_core_extensions` v4.0, so this is getting
out ahead of that.

Note:  The change to add `.to_a` is ahead of `.tabular_sort` is because
`Ruport::Data::Table` inherits from `Enumerable` and not `Array`, but
`.tabular_sort` was implemented only on `Array`.  Should still work the
same, though.

app/models/miq_report_result/result_set_operations.rb

@@ -45,7 +45,7 @@ def result_set_for_reporting(report_result, options)
         end
 
         result_set.map! { |x| x.slice(*report.col_order) }
-        result_set = result_set.stable_sort_by(sorting_columns, options[:sort_order])
+        result_set = result_set.tabular_sort(sorting_columns, options[:sort_order])
         result_set = apply_limit_and_offset(result_set, options)
       end
 

lib/patches/ruport_patch.rb

@@ -6,7 +6,7 @@
 module Ruport::Data
   class Table
     def sort_rows_by(col_names = nil, options = {}, &block)
-      self.class.new(:data         => stable_sort_by(col_names, options[:order], &block),
+      self.class.new(:data         => to_a.tabular_sort(col_names, options[:order], &block),
                      :column_names => @column_names,
                      :record_class => record_class)
     end