Feature suggestion: lib_upgrade()

[rossellhayes]

I see from #168 and #639 that there's interest in a function to upgrade all installed packages. I've been working on a function to do this: https://github.com/rossellhayes/upgrade/blob/main/R/pkg_upgrade.R

I completely understand if it's not up to the standard of this package. But if it would be useful, I'd be happy to submit the code as a PR.

[gaborcsardi]

Thanks! Yes, as you noticed, upgrading everything is challenging, and a lot of times just won't work, especially if you installed packages from non-CRAN sources.I hope we'll be able to have a function for this soon.