Use public API only

[maennchen]

The commands currently use two private modules:

• Mix.Dep.Lock – Load locked dependencies
• IO.ANSI.Docs – Format output (Important for Markdown content of vulnerability description)

In my humble opinion, both of those have the potential to be public since they offer functionality that can be reused in a lot of other code.

I would recommend asking the elixir core team if those API's could be opened and if not we'll have to find a way without touching private apis.