ggplot2::sec_axis is unsupported #2451

Hello!

When I use ggplot2::scale_y_continuous(sec.axis = ggplot2::sec_axis(~ . / scale_factor)) like this, I discovered that plotly does not support this function. Providing support for this function would greatly assist developers like myself who are accustomed to ggplot but wish to utilise plotly's interactive capabilities.

Thanks.