Improve context product validation to ensure the context product type matches the type specified

[jordanpadams]

This currently validates successfully but should obviously not:

      <Observing_System_Component>
        <name>InSight</name>
        <type>Spacecraft</type>
        <Internal_Reference>
          <lid_reference>urn:nasa:pds:context:target:planet.earth</lid_reference>
          <reference_type>is_instrument_host</reference_type>
          <comment>This is the PDS4 logical identifier for the InSight Lander spacecraft.</comment>
        </Internal_Reference>
      </Observing_System_Component>