anari: Use the volume bounds for origin

This allows volumes with negative extents to be properly propogated to the anari scenegraph.

Rendering/ANARI/Testing/Data/Baseline/TestAnariVolumeWavelet.png.sha512

-aa5e7f9a2af603c366ba7573effadfa1339d147afa8d83c198bc426227a8dc1a235dc9136b589cd13fb71dccdaae6986a82d43792ef8502d9ec1fd64f5b1364b
+3dd21468cbdb814d0bb0a0faaedd1238f5558842d66d3763797c81e9ed6d4b44ae556c5454bd3da4239f6178081cf0fd325fe06c3d1cdbfacd2bc8460d713a8a

Rendering/ANARI/vtkAnariVolumeMapperNode.cxx

@@ -353,8 +353,10 @@ void vtkAnariVolumeMapperNode::Render(bool prepass)
         anari::newObject<anari::SpatialField>(anariDevice, "structuredRegular");
 
       double origin[3];
-      data->GetOrigin(origin);
-
+      const double* bds = vol->GetBounds();
+      origin[0] = bds[0];
+      origin[1] = bds[2];
+      origin[2] = bds[4];
       vec3 gridOrigin = { static_cast<float>(origin[0]), static_cast<float>(origin[1]),
         static_cast<float>(origin[2]) };
       anari::setParameter(anariDevice, anariSpatialField, "origin", gridOrigin);