`filter()` should error for named input

[mgirlich]

This dplyr feature is pretty handy against typos 😄

library(dplyr, warn.conflicts = FALSE)
library(dtplyr)

mtcars %>% filter(mpg = 1)
#> Error: Problem with `filter()` input `..1`.
#> x Input `..1` is named.
#> ℹ This usually means that you've used `=` instead of `==`.
#> ℹ Did you mean `mpg == 1`?
lazy_dt(mtcars) %>% filter(mpg = 1)
#> Source: local data table [1 x 11]
#> Call:   `_DT1`[1]
#> 
#>     mpg   cyl  disp    hp  drat    wt  qsec    vs    am  gear  carb
#>   <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl>
#> 1    21     6   160   110   3.9  2.62  16.5     0     1     4     4
#> 
#> # Use as.data.table()/as.data.frame()/as_tibble() to access results

^{Created on 2021-07-02 by the reprex package (v2.0.0)}