Add unit tests for non-syntactic column names

[ddsjoberg]

At first look, it seems they work well. But should do some more testing and add unit tests so we don't accidentally break it in the future.

• [x] Ensure non-syntactic names work as variables
• [x] Ensure non-syntactic names work as by/strata variables
• [x] Can function names in tbl_continuous() have non-syntactic names? Or named list inputs, like the formatting functions and statistic labels, etc.

library(cards)

ADSL |> 
  dplyr::mutate(`Age Group` = AGEGR1) |> 
  ard_categorical(variables = `Age Group`) |> 
  head(2)
#> {cards} data frame: 2 x 9
#>    variable variable_level   context stat_name stat_label statistic
#> 1 Age Group            <65 categori…         n          n        33
#> 2 Age Group            <65 categori…         N          N       254
#> ℹ 3 more variables: statistic_fmt_fn, warning, error

ADSL |> 
  dplyr::mutate(`Age Group` = AGEGR1) |> 
  ard_categorical(variables = "Age Group") |> 
  head(2)
#> {cards} data frame: 2 x 9
#>    variable variable_level   context stat_name stat_label statistic
#> 1 Age Group            <65 categori…         n          n        33
#> 2 Age Group            <65 categori…         N          N       254
#> ℹ 3 more variables: statistic_fmt_fn, warning, error

ADSL |> 
  dplyr::mutate(`Patient Age` = AGE) |> 
  ard_continuous(variables = `Patient Age`) |> 
  head(2)
#> {cards} data frame: 2 x 8
#>      variable   context stat_name stat_label statistic statistic_fmt_fn
#> 1 Patient Age continuo…         N          N       254                0
#> 2 Patient Age continuo…      mean       Mean    75.087                1
#> ℹ 2 more variables: warning, error

ADSL |> 
  dplyr::mutate(`Patient Age` = AGEGR1) |> 
  ard_continuous(variables = "Patient Age") |> 
  head(2)
#> {cards} data frame: 2 x 8
#>      variable   context stat_name stat_label statistic   warning
#> 1 Patient Age continuo…         N          N       254          
#> 2 Patient Age continuo…      mean       Mean        NA argument…
#> ℹ 2 more variables: statistic_fmt_fn, error

^{Created on 2024-02-11 with reprex v2.1.0}