The uninstallation logic is similar to firenvim#install:
At first, is_wsl is set to false, even on WSL. This lets us uninstall
firenvim on the wsl side.
Then, we set is_wsl to true if we're on wsl and launch
firenvim#uninstall again, uninstalling things on the host side.
The uninstallation logic is similar to
firenvim#install
: