Should we delete `.julia/juliaup` at uninstall?

At the moment `juliaup self uninstall` deletes that folder. Question is: should we? We are not really uninstalling anything else from `.julia` with this command, so the question is a bit why are we uninstalling that one specific folder?

An alternative could be that the `self uninstall` really only uninstalls the things that make up Juliaup itself, i.e. the things that get installed into `~/.juliaup` (the launcher and `juliaup` binary and the self hosting config file, essentially). That would make it more symmetric with platform package manager installed versions of Juliaup as well, for example when a user uninstalls the Windows Store version of Juliaup, `.julia/juliaup` is _not_ removed.

Another argument for this is that Juliaup can manage any Julia depot, depending on what value the env variable `JULIA_DEPOT` currently has. Maybe it is weird that the uninstall command would just handle _one_ depot in that case?

On the flipside, it does free up space... Unclear to me what the right choice here is.

Again, @StefanKarpinski would be great if you could chime in on this.

Read the implementation behind `juliaup self uninstall` and trace how it selects `.julia/juliaup`, `~/.juliaup`, and the `JULIA_DEPOT` value. Compare the behavior with platform package-manager uninstallations; done means a decided scope for removal, documented behavior, and matching tests.

Written by the indexing model from the issue text.