pkgin fug should print a warning about deprecation

[gdt]

Now that upgrade (ug) is upgrade all, fug makes no sense and the user should be warned on stderr to use ug instead.

[gdt]

Still an issue in 23.8.0.

[jperkin]

Yeh I've not added this yet.

[gdt]

Not a complaint; you have closed a huge number of bugs and I went over all mine that were open to validate that they still should be.