Support material property integration and volume averaging in ExtraIDIntegralVectorPostprocessor

[NamjaeChoi]

Motivation

In Griffin, material properties are used to store isotopic number densities outputted from depletion. To obtain integrated or averaged number density of nuclides over a certain domain defined by an extra element ID, ExtraIDIntegralVectorPostprocessor should support integrating or averaging material properties as well.

Design

Add a parameter average to specify whether the user wants integration or averaging. Also add a parameter mat_prop to specify the list of material properties the user wants to integrate or average.

Impact

More convenient data postprocessing.