Fix breakage due to recent change in tabulated-list-print-entry

Fix breakage due to recent change in tabulated-list-print-entry

* lisp/emacs-lisp/tabulated-list.el (tabulated-list-printer):
Update the doc string.
(tabulated-list-print-entry): Revert to using only 2 arguments.
Update the doc string.
(tabulated-list-entry-lnum-width): New defvar.
(tabulated-list-print): Compute the width of line-number display
once, then store that value in tabulated-list-entry-lnum-width,
for tabulated-list-printer to use.  (Bug#28704)