Test to image instead of playground

aiks_unittests.cc

TEST_P(AiksTest, CanRenderStrokes) {
  Canvas canvas;
  Paint paint;
  paint.color = Color::Red();
  paint.stroke_width = 20.0;
  paint.style = Paint::Style::kStroke;
  canvas.DrawPath(PathBuilder{}.AddLine({200, 100}, {800, 100}).TakePath(),
                  paint);
  Picture picture = canvas.EndRecordingAsPicture();
  std::shared_ptr<Image> image = picture.ToImage(GetContext(), {1000, 1000});
}