Flip radius axis in coord_radial() when position = "right"/"top"

[teunbrand]

This PR aims to fix #5735.

Briefly, when the scale's position argument is set to a secondary position (right/top), the radius axis will be swapped with the secondary radius axis (which is typically a 'none' guide).

A demo:

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

p <- ggplot(mpg) +
  geom_boxplot(aes(x = class, y = displ)) +
  scale_y_continuous(position = "right")

p + coord_radial()

p + coord_radial(r_axis_inside = TRUE)

^{Created on 2024-03-05 with reprex v2.1.0}

[thomasp85]

LGTM