Add a reinstall command

Sometimes, especially during development and troubleshooting, it would be nice to be able to reinstall a version in a similar manner to Homebrew. In its primitive form, it could be just `uninstall` and `install` chain, but take further, it could be done transactionally, too, i.e. a failure to install won't remove the previous instance.

The issue names no files, tests, or entry points; begin by locating the existing install and uninstall CLI commands. Define the reinstall behavior, including whether it is a simple uninstall/install chain or transactional, and verify that a failed install preserves the previous instance.

Written by the indexing model from the issue text.