Add a `--recursive=<true|false>` param to `pkg ldd` command

Add a param that lets users enable/disable dependency checking with the ldd command.

With recursive=false, ldd should check only the given package, not its deps as well...

This would make the following work much nicer:

Check for missing deps in all user installed packages:

pkg li | pkg ldd -

or

Check for missing deps in ALL installed packages (including built-ins):

pkg LI | pkg ldd -