add support for R via renv

testing/get-r.sh

@@ -0,0 +1,9 @@
+#!/usr/bin/env bash
+sudo apt install r-base
+# create empty folder for user library.
+# necessary for non-root users who have
+# never installed an R package before.
+# Alternatively, we require the renv
+# package to be installed already, then we can
+# omit that.
+Rscript -e 'dir.create(Sys.getenv("R_LIBS_USER"), recursive = TRUE)'