message: Use marble as default in editor
  This changelist assigns standard_surface_marble_solid.mtlx as the default material in the graph editor.
diff: @@ -77,7 +77,7 @@ int main(int argc, char* const argv[])
  tokens.emplace_back(argv[i]);
  }
  - std::string materialFilename = "resources/Materials/Examples/StandardSurface/standard_surface_default.mtlx";
  + std::string materialFilename = "resources/Materials/Examples/StandardSurface/standard_surface_marble_solid.mtlx";
  std::string meshFilename = "resources/Geometry/shaderball.glb";
  mx::FileSearchPath searchPath = getDefaultSearchPath();
  mx::FilePathVec libraryFolders;
  