Add support for more selected/unselecter marker attributes for scattermapbox

[jackparmer]

https://codepen.io/plotly/pen/mXrQZg?editors=0010

[etpinard]

This is known limitation from f54a08a

Changing this to type: feature

[jackparmer]

selected.marker.opacity does not seem to work either with the latest Plotly.js:

https://codepen.io/plotly/pen/oEzJXQ?editors=0010

[jackparmer]

Here's another example of this issue with selected.marker.opacity. Try setting the unselected opacity to 0 in this plotly.js mock:

https://codepen.io/plotly/pen/NyRedR?editors=0010

The current behavior is basically no different than without the selections API.