Add "back" button on top of the pre-rename vc-print-log buffer

Add "back" button on top of the pre-rename vc-print-log buffer

* lisp/vc/vc.el (log-view-vc-prev-revision)
(log-view-vc-prev-fileset): New dynamic variables (bug#55871).
(vc-print-log-renamed-add-button): Extract from
'vc-print-log-setup-buttons'.  Bind the above variables to convey
the current revision and fileset to 'vc-print-log-internal'.
(vc-print-log-internal): Use it also here, to print a "back"
button above the log when 'log-view-vc-prev-fileset' is set.