bug#1305: All code that currently beeps should use visual bell instead

[Eli Zaretskii]

> From: Lars Ingebrigtsen <larsi@gnus.org>
> Date: Sun, 18 Apr 2021 14:36:55 +0200
> Cc: Michael Welsh Duggan <mwd@md5i.com>,
>  Gregory Heytings <gregory@heytings.org>, 1305@debbugs.gnu.org,
>  jasonspiro4@gmail.com, monnier@iro.umontreal.ca
> 
> As somebody else noted earlier, if you have visible-bell on, but use
> "-nw", that's the only notification you get -- there's no visible bell
> on the console.

Is that really true?  I see in the code that we do support
visible-bell on TTY frames if terminfo says the terminal is capable of
doing that, see term.c:tty_ring_bell.