Binned scales and date(time) transformations

[teunbrand]

This PR aims to fix #4217 and part of #4982.

Briefly, it avoids setdiff(), which strips attributes, and multiplication, which is incompatible with dates.

A small demonstration:

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

ggplot(economics, aes(date)) +
  stat_summary(aes(y = unemploy)) +
  scale_x_binned(trans = "date")
#> No summary function supplied, defaulting to `mean_se()`

ggplot(economics, aes(date, unemploy, colour = date)) +
  geom_line() +
  scale_colour_stepsn(
    colours = rainbow(10),
    trans = "date"
  )

^{Created on 2022-12-11 by the reprex package (v2.0.1)}

[thomasp85]

LGTM