Swap vec_in() for %in%

[teunbrand]

This PR to the RC aims to fix a bug uncovered in revdepchecks affecting ~19 packages.

One such example is this:
https://github.com/tidyverse/ggplot2/blob/rc/3.5.0/revdep/problems.md#newly-broken-119

Briefly, vec_in() is too strict in that it cannot compare incompatible vectors, like logical and character vectors.
To reproduce this error, combine a logical and character level for the same aesthetic.
The fix is to replace vec_in() with %in%.

library(ggplot2) # RC branch

ggplot(mpg, aes(displ, hwy)) +
  geom_point(aes(colour = hwy > 30)) +
  geom_line(aes(colour = "foo"))
#> Error in `vec_in()` at ggplot2/R/guide-legend.R:727:5:
#> ! Can't combine <character> and <logical>.

How it should work:

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

ggplot(mpg, aes(displ, hwy)) +
  geom_point(aes(colour = hwy > 30)) +
  geom_line(aes(colour = "foo"))

^{Created on 2023-12-21 with reprex v2.0.2}

[thomasp85]

LGTM, but please don't use the default windows graphic device 😛

[teunbrand]

But how else am I going to see all them aliased pixels 😱