I'm considering two ways of implementing this. First option is to place a save_all() function into R/utils.R. I'm not sure that this is the best location, if we are anticipating expanding with impls for other editors. In that case, it makes more sense to me to create R/save-all.R, and export the function from that file.
I think we should put it in R/save-all.R with an eye towards expanding the functionality to other editors in the future. Although doing so would likely require a package to communicate with them ala rstudioapi.