unnecessary_placeholder_linter() could cover other magrittr operators too

[MichaelChirico]

Follow-up to #1656

IINM, %<>% and %T>% should work out of the box if we expand text() in XPath.

The %$% is a bit more tricky and can possibly be dealt with separately.

WDYT?

library(magrittr)

y <- 1
y %<>% sum(., 1) # lint
y
#> [1] 2

z <- 1
z %<>% sum(1)
z
#> [1] 2

# N.B. removing plots output manually to keep the reprex clean
1 %T>% plot %>% sum(1)
#> [1] 2
1 %T>% plot() %>% sum(1)
#> [1] 2
1 %T>% plot(.) %>% sum(1) # lint
#> [1] 2

mtcars %$% cor(wt, mpg)
#> [1] -0.8676594
mtcars %$% cor(.$wt, .$mpg) # lint
#> [1] -0.8676594

<sup>Created on 2022-10-10 with [reprex v2.0.2](https://reprex.tidyverse.org)</sup>

Originally posted by @IndrajeetPatil in #1656 (comment)

[MichaelChirico]

This was done in #2046