message: gltfpack: Add image compression verbose output
  When Basis compression is enabled, it takes a lot of time. Since we
  mostly run compression from memory, it's not as easy to print an
  accurate progress note from encodeBasisFile but we can just as easily do
  it before calling writeImage.
diff: @@ -3540,6 +3540,14 @@ void process(cgltf_data* data, const char* input_path, const char* output_path,
  for (size_t i = 0; i < data->images_count; ++i)
  {
  + if (settings.verbose && settings.texture_basis)
  + {
  + const char* uri = data->images[i].uri;
  + bool embedded = !uri || strncmp(uri, "data:", 5) == 0;
  +
  + printf("image %d (%s) is being encoded with Basis\n", int(i), embedded ? "embedded" : uri);
  + }
  +
  writeImage(json_images, views, data->images[i], images[i], i, input_path, output_path, settings);
  }
  