GDB completions in dexed debugger GUI

[Basile B.]

For those who are not aware, GDB completion in CLI (TAB) is not 
just like standard bash completions, that also allows to complete 
using DWARF informations, very similarly to IDE completion.

[Dexed-ide](https://gitlab.com/basile.b/dexed/-/releases/v3.9.20) 
debugger (aka "GDB Commander") now support this feature:

short video demonstration: 
https://www.youtube.com/watch?v=hZYslYFohrI