Reverse dodging

[teunbrand]

This PR aims to fix #3610.

Briefly, it adds a reverse argument to position_dodge() and position_jitterdodge() that reverses the groups within a position in terms of dodge order.

As a detail, for consistency with position_dodge2(), we actually pass !reverse to collide().

Adapted reprex from issue:

devtools::load_all("~/packages/ggplot2")
#> ℹ Loading ggplot2

p <- ggplot(mtcars) +
  aes(
    as.factor(cyl), mpg, 
    fill = as.factor(vs), 
    group = interaction(cyl, vs)
  )

p + 
  geom_boxplot(position = position_dodge(reverse = FALSE)) +
  geom_point(position = position_jitterdodge(reverse = FALSE), shape = 21)

p + 
  geom_boxplot(position = position_dodge(reverse = TRUE)) +
  geom_point(position = position_jitterdodge(reverse = TRUE), shape = 21)

^{Created on 2024-05-31 with reprex v2.1.0}

[thomasp85]

LGTM