Support viewing VC change history across renames (Git, Hg)

Support viewing VC change history across renames (Git, Hg)

* lisp/vc/vc.el (vc-print-log-setup-buttons):
When the log ends at a rename, add a button to jump to the
previous names.  Use the new backend action 'file-name-changes'.

* lisp/vc/vc-git.el (vc-git-print-log-follow): New option.
(vc-git-file-name-changes): Implementation (bug#55871, bug#39044).
(vc-git-print-log-follow): Update docstring.

* lisp/vc/log-view.el (log-view-find-revision)
(log-view-annotate-version): Pass the log's VC backend explicitly.

* lisp/vc/vc-hg.el (vc-hg-file-name-changes):
Add Hg implementation (bug#13004).

* etc/NEWS: Mention the changes.