Download + install in add command

[jonashaag]

Currently the add command doesn't download + install the package.

Maybe there are good reasons to do it that way but I think I would actually prefer it to be done in the add step. From a UX perspective, I'd rather wait one longer time than two smaller times.

I guess doing the installation in add also opens up some possibilities for reducing the total wall time spent waiting, maybe by doing stuff concurrently.

What's the use case for separating the two? When would you want add to not actually download and install?

[baszalmstra]

I dont see a reason why we shouldnt do that. Ill create a PR.