Fix add_years translation on spark

[ablack3]

Addresses issue #1510

[simonpcouch]

Thanks for the PR! Confirming that it indeed works using the reprex from the issue:

library(odbc)
library(clock)
library(dplyr)
#> 
#> Attaching package: 'dplyr'
#> The following objects are masked from 'package:stats':
#> 
#>     filter, lag
#> The following objects are masked from 'package:base':
#> 
#>     intersect, setdiff, setequal, union

con <- dbConnect(databricks(), HTTPPath = "/sql/1.0/warehouses/300bd24ba12adf8e")

df <- data.frame(x = as.POSIXct("2000-01-01"))
copy_to(con, df)

q <- tbl(con, "df") %>% mutate(y = add_years(x, 1))

q %>% show_query()
#> <SQL>
#> SELECT `df`.*, ADD_MONTHS(`x`, 1.0 * 12.0) AS `y`
#> FROM `df`

q %>% collect()
#> # A tibble: 1 × 2
#>   x                   y         
#>   <dttm>              <date>    
#> 1 2000-01-01 06:00:00 2001-01-01

^{Created on 2024-08-27 with reprex v2.1.1}

Could you please add a NEWS entry describing the changes?

[simonpcouch]

Hey @ablack3, would be glad to bring these changes into dbplyr with the changes suggested above! Would you be interested in finishing this one off by adding a NEWS entry?