Fix bugs in tab-bar and tab-line and mention remaining features in manual.

Fix bugs in tab-bar and tab-line and mention remaining features in manual.

* doc/emacs/frames.texi (Tab Bars): Mention tab-bar-new-tab-to,
tab-bar-close-last-tab-choice, tab-bar-close-tab-select, tab-undo,
tab-select, tab-bar-history-mode.

* doc/emacs/windows.texi (Tab Line): Mention tab-line-tabs-function.

* lisp/tab-bar.el (tab-bar-select-tab-modifiers): Mention
tab-bar-tab-hints in docstring.
(tab-bar-tab-hints): Mention tab-bar-select-tab-modifiers
in docstring.
(tab-bar-select-tab): Mention tab-bar-select-tab-modifiers
in docstring.
(tab-bar-switch-to-tab): Expand the docstring.
(tab-bar-new-tab-to): Fix bug in handling 'left' value.
(tab-bar-close-tab): Fix bug in handling 'left' value.
(tab-bar-undo-close-tab): Use funcall tab-bar-tabs-function
instead of direct call to tab-bar-tabs.
(tab-bar-history-back, tab-bar-history-forward): Add docstrings.
(tab-bar-history-mode): Expand docstring.

* lisp/tab-line.el (tab-line-format): Fix bug for handling window
switching that should set face 'tab-line-tab-current'.