Feature: Migrating Global Packages While Installing

[Belco90]

Hi there! fnm is amazing, I'm using it in both my personal and work MacBook Pro 👌

I just miss one feature from nvm tho: being able to migrate global packages while installing.

It would be great if fnm added a new --reinstall-packages-from option for install command, which allows you to specify from which installed version you want to migrate packages installed. This is really convenient when installing new versions to replace existing ones.

Thanks!