test: add support for gl2d in compare pixel test routine
test: add support for gl2d in compare pixel test routine

- warn when gl2d are ran batch
- skip over multiple subplot test on CI, see
  https://github.com/plotly/plotly.js/pull/980
  for details

iongroup/plotly.js,iongroup/plotly.js,aburato/plotly.js,asolagmbh/plotly.js,plotly/plotly.js,asolagmbh/plotly.js,etpinard/plotly.js,plotly/plotly.js,plotly/plotly.js,aburato/plotly.js,plotly/plotly.js,etpinard/plotly.js,asolagmbh/plotly.js,iongroup/plotly.js,etpinard/plotly.js