build a list of packages that often require internet access

[rosemm]

Can potentially use something like names(sessionInfo()$loadedOnly) to check the user's list of loaded packages against our list of packages that might need an internet connection (like devtools, rvest, httr, curl, etc.) and print a warning if they're in offline mode but have loaded a package that likely needs internet.

[rosemm]

Also possibly of use: https://developer.r-project.org/Blog/public/2019/03/19/managing-search-path-conflicts/