feat: add support for 'asdf' sdk manager

[fragonib]

Context

asdf is a great SDK manager but dotly has no support to dump/import its managed packages.

Goal

This PR introduce minimal support for dump/import SDK managed packages by ASDF until later has native support for dumping/importing SDKs.

[BoscoDomingo]

Could you make this work for rtx too? it's an awesome alternative to asdf

[fragonib]

I didn't know about It. Let me have a look...