TST: add render testing, mark as xslow#39

yuxuanzhuang merged 6 commits intoyuxuanzhuang:mainyuxuanzhuang/ggmolvis:mainfrom

tylerjereddy:treddy_render_test_demo_xslowtylerjereddy/ggmolvis:treddy_render_test_demo_xslowCopy head branch name to clipboard