Add fix to take account of linebreaks in yaxis ticklabels.

[trekonom]

This PR proposes a fix to take account of linebreaks in yaxis ticklabels.

At present ggplotly does not take linebreaks in y-axis labels into account when computing the margins. Hence, the left margin is set too wide in that case.

The issue can be illustrated with this reprex:

library(plotly)

d <- data.frame(x = c(1, 2), y = c("dfdfjdfdf\ndjdfkjdfdklj\nsldflkfdlf", "dfdfjdfdf"))

ggplot(d, aes(x, y)) +
  geom_bar(stat = "identity")

ggplotly()

At present this is rendered with a lot of white space to the left of the axis labels:

With the proposed fix the reprex is rendered like so:

As a workaround to this issue one can force automargin to do its job by setting the left margin to a small number in the layout options like so:

ggplotly() %>%
    layout(margin = list(l = 0))