Add a skip method for ranget

Author: romainbrenguier

src/util/range.h

@@ -353,6 +353,16 @@ struct ranget final
     }
   }
 
+  /// Return an new range containing the same elements except for the first
+  /// \p count elements.
+  /// If the range has fewer elements, returns an empty range.
+  ranget<iteratort> skip(std::size_t count) const
+  {
+    ranget<iteratort> skip_range{begin(), end()};
+    skip_range.drop(count);
+    return skip_range;
+  }
+
   iteratort begin() const
   {
     return begin_value;