Add --prefer-offline / MISE_PREFER_OFFLINE

[jdx]

Discussed in #3928

^{Originally posted by hverlin January 3, 2025}
Add a --prefer-offline flag / MISE_PREFER_OFFLINE environment variable for a few commands like mise doctor. I imagine this can be useful in various context when the internet speed is low or when one wants a command to return as fast as possible.

This is obviously not going to work with every command (like mise install) however.

[weyert]

Does this fix the issue that you can't use Mise when you don't have internet? E.g. on an airplane? I tried to do some development work while flying. Only the Wi-Fi on the plane didn't work and ended being unable to use Mise at all. I didn't expect I wouldn't be able to use Mise without internet connectivity. Ended up packing up my laptop again and listen to audiobooks for 12 hours