bug#51935: 29.0.50; tab-switch hides identically named tabs

[Juri Linkov <juri@linkov.net>]

close 51935 29.0.50
thanks

> Depending on the configured completion framework C-x t RET will show
> candidates in order or not, but the interpretation of the suffix as a
> position seems relatively clear to me even in the unordered case, if
> not anything else at least it's an indication that there are
> additional tabs with the same name.

Actually, not only tab-bar-switch-to-tab has such function signature
that uses the argument NAME, but also other functions such as
tab-bar-close-tab-by-name and tab-bar-rename-tab-by-name.
All they expect a unique name of the tab.  There is no way
to distinguish tabs with the same name.  In practice,
this problem doesn't exist because in this case
the users just rename the tab to a unique name.

To make is more easy to rename the tab, I improved 'C-x t RET' in master
that now it creates a new tab when the provided tab name doesn't exist.
So instead of using 'C-x t 2' to create a new tab, you can use
'C-x t RET new-tab-name RET', exactly in the same way as
'C-x b new-buffer RET' can be used to create a new buffer.