New xref-quit-and-goto-xref command bound to TAB (bug#28814)

New xref-quit-and-goto-xref command bound to TAB (bug#28814)

This is like xref-goto-xref, but quits the *xref* window just before
the user jump to ref.

* lisp/progmodes/xref.el (xref--show-location): Handle 'quit
value for SELECT.
(xref-goto-xref): Take optional QUIT arg.
(xref-quit-and-goto-xref): New command.
(xref--xref-buffer-mode-map): Bind "Q" and "TAB" to
xref-quit-and-goto-xref.

* doc/emacs/maintaining.texi (Xref Commands): Describe new bindings in
*xref*.

* etc/NEWS (Xref): Describe new binding.