Dry-run based testing for correct dockerization

[chainsawriot]

GHA can be later; but at least local should be fine.

temp=`mktemp -d`                                                                          
Rscript -e "rang::dockerize(rang::resolve(\"cran/sna\", snapshot_date = \"2005-10-01\"), cache = TRUE, output_dir = \"$temp\")"; docker build -t test $temp

[chainsawriot]

Test case for #99 Pre 3.1

graph <- resolve("github::cran/psych", snapshot_date = "2013-01-01")

Test case for #99 Post 3.1 and with knitr

graph <- resolve("github::chainsawriot/rang", snapshot_date = "2023-01-01")

[chainsawriot]

Dependencies heaven

graph <- resolve("chimeraviz", snapshot_date = "2023-01-01")

[chainsawriot]

graph <- resolve("github::chainsawriot/rang", snapshot_date = "2023-01-01")
dockerize(graph, ".", cache = TRUE) ## test caching / raw tarball
dockerize(graph, ".", cache = FALSE) ## test raw download / raw tarball