Add option "notch" (and "notchwidth") to geom_boxplot

I would like to add notches to boxplots like it is possible in ggplot. The feature has recently been implemented for the plotly API (https://community.plot.ly/t/add-option-notch-to-box-plots/7396/3)

library(plotly)

set.seed(1234)
dat <- data.frame(cond = factor(rep(c("A","B"), each=200)), rating = c(rnorm(200),rnorm(200, mean=.8)))

p <- ggplot(dat, aes(x=cond, y=rating)) + geom_boxplot(notch = TRUE)

# ggplot shows notch
p

# ggplotly does not
ggplotly(p)

首先使用 ggplot、geom_boxplot(notch = TRUE) 和 ggplotly(p) 重现 issue 中的 R 示例，然后检查 plotly.R 如何转换 geom_boxplot。当 ggplotly 保留箱线图的 notch 并支持 notchwidth，且不会丢失现有图表时，即表示完成。