* lisp/tab-line.el (tab-line-force-update): New function (bug#71601).

* lisp/tab-line.el (tab-line-force-update): New function (bug#71601).

(tab-line-tab-name-function, tab-line-tabs-function)
(tab-line-tabs-buffer-group-function)
(tab-line-tabs-buffer-group-sort-function)
(tab-line-tabs-buffer-groups-sort-function)
(tab-line-tab-name-format-function):
Use 'tab-line-force-update' in the :set lambda of defcustom.
(tab-line-tab-name-function, tab-line-tabs-function)
(tab-line-cache-key-function): Mention 'tab-line-force-update'
in the docstring.
(tab-line-new-button-show, tab-line-close-button-show):
In the :set lambda of defcustom use 'force-mode-line-update'
with the non-nil arg ALL.