Enhancement: Better prompt when existing configuration

[kdheepak]

Currently there's no information about where the configuration file is located when the old installation is incompletely removed:

It would be good if the prompt told the user where the old file was (or showed the contents of the old file?) so that the user can make a more informed decision about how to act given this prompt

[kdheepak]

There's also no option to continue with the installation and not overwrite the existing juliaup configuration file, which makes it more work if the user wants to go down that path.