feature request: make package list sortable by columns

[loa-in-]

I wanted to sort my updates by architecture earlier today, but I couldn't.
This program is my main package manager, but lacks usability features. Unfortunately I am not familiar enough with C/C++ to do it.

[genodeftest]

As far as I can remember, the old yumex (for yum, not dnf) had this feature. I think it was removed for performance reasons. I'd like to see this feature back too, but have no time to do so.

Anyway, yumex-dnf is not written in C/C++ but in python which takes like 1 day to learn if you've learned a different programming language before.

I've already done some mockups which need a little improvement (#74), but that's a another possible solution.

[spariant]

I would very much also like this, in my case for sorting packages by size.

[spariant]

Hi genodeftest. I realize that this can be a simple solution for reauest #89 . No need for additional ui buttons whatsoever.