separate env_vars for private variables

[maelle]

if there were a separate check_args argument for private variables, there could be a separate field in the API response, and then one could include non private private variables in default printing methods.

[gaborcsardi]

You mean env_vars?

[maelle]

oops yes

[gaborcsardi]

This is not only up to the R package, but the builders should know about it as well, e.g. not to list them in the logs. So this will be postponed until rhub-server is deployed.

[gaborcsardi]

This issue is about the previous R-hub system, it does not apply to the new system, so I am closing it now. Please see https://r-hub.github.io/rhub/ for the new system, R-hub v2.