bug#10107: 23.2; Add command gud-quit

[Eli Zaretskii]

> From: Krzysztof Żelechowski <giecrilj@stegny.2a.pl>
> Date: Sun, 06 Jun 2021 15:04:27 +0200
> Cc: 10107@debbugs.gnu.org
> 
> > (Assigning a keystroke to it might perhaps be overkill.)
> 
> Imagine yourself as an operator at the Knight Capital Group.  You can see 
> ongoing damage but you still want to preserve the log.  What would you rather 
>  
> use, a keyboard accelerator or a long command?

Any user can always bind this command to any key they want.  Lars was
talking about having a binding _by_default_.