feat: Extend unused_function to other R package folders

[etiennebacher]

Check that functions defined in inst/tinytest, inst/tests, and tests are used in those folders. Note that while functions defined in R can be used in tests, the opposite is not true.

[github-actions]

Ecosystem checks

Rdatatable/data.table: +1 -0 violations

New violations (first 100):

tests/autoprint.R[62:0]: unused_function -- `print.foo` is defined but never called in this package.  

ropensci/targets: +2 -0 violations

New violations (first 100):

tests/testthat/helper-aws.R[42:0]: unused_function -- `aws_s3_delete_targets_buckets` is defined but never called in this package.
tests/testthat/helper-gcp.R[13:0]: unused_function -- `gcp_gcs_delete_targets_buckets` is defined but never called in this package.  

rstudio/shiny: +2 -0 violations

New violations (first 100):

tests/testthat/helper.R[74:0]: unused_function -- `rewire_namespace_handler` is defined but never called in this package.
tests/testthat/test-stacks.R[112:0]: unused_function -- `dumpTests` is defined but never called in this package.  

tidyverse/dplyr: +1 -0 violations

New violations (first 100):

tests/testthat/helper-encoding.R[27:0]: unused_function -- `get_alien_lang_string` is defined but never called in this package.  

tidyverse/ggplot2: +2 -0 violations

New violations (first 100):

tests/testthat/test-facet-labels.R[18:0]: unused_function -- `get_labels_info.FacetGrid` is defined but never called in this package.
tests/testthat/test-facet-labels.R[31:0]: unused_function -- `get_labels_info.FacetWrap` is defined but never called in this package.  

[github-actions]

Benchmark on real-projects

Repository	Avg. duration (main, seconds)	Avg. duration (PR, seconds)	PR - main	PR - main (%)	Number of iterations
easystats/datawizard	0.1966549	0.2021948	0.0055399244	2.8170798	50
lrberge/stringmagic	0.1820837	0.1812051	-0.0008786573	-0.4825567	50
pola-rs/r-polars	0.2499054	0.2559953	0.0060899545	2.4369042	50
Rdatatable/data.table	0.2333518	0.2358466	0.0024948052	1.0691177	50
ropensci/targets	0.4115552	0.4193643	0.0078090645	1.8974525	50
rstudio/shiny	0.2106204	0.2131868	0.0025663975	1.2184942	50
tidyverse/dplyr	0.2449498	0.2494984	0.0045485864	1.8569464	50
tidyverse/ggplot2	0.3735404	0.3796126	0.0060722614	1.6255972	50
vincentarelbundock/marginaleffects	0.2092290	0.2129781	0.0037491816	1.7919038	50
wch/r-source	1.8342253	1.8506964	0.0164710488	0.8979839	50