bug#38693: 27.0.50; tab-bar: automatic tab names should be shortened

[Juri Linkov]

> Dear emacs developers, Juri, per default tab-bar uses buffer
> names as tab labels.  But these might be very looong:

I've never seen that long buffer name before.
This reminds Guinness Book record for the longest name :)

> Please provide an option to dynamically shorten at least
> automatic tab labels in order not to overflow the tab bar into
> another line OR provide an option with sensible default for the
> max length of automatic tab labels (e.g. 23 characters per tab
> label would allow for at least 3 tabs on a 80 char terminal) OR
> something to such effect.

Maybe such a new option:

  (defcustom tab-bar-tab-name-max 23

and using it on the default values of tab-bar-tab-name-current,
tab-bar-tab-name-current-with-count, tab-bar-tab-name-all?