Make it compatible with Hugo 0.55 (#13680)

This commit adds two backwards compatible changes to prepare for the next Hugo version, most notable:

* All the `File` methods on `Page` has been deprecated and will give a warning in the next Hugo version. Adjust this by changing `.Dir` to ´.File.Dir` and similar.
* Version the capture shortcode to use the old behaviour for markdown rendering of shortcode inner content.

layouts/partials/git-info.html

@@ -19,7 +19,7 @@
     {{ end }}
     {{ end }}
     {{ if not .Params.noedit }}
-    <a href="https://github.com/kubernetes/website/edit/master/content/{{ site.Language.Lang }}/{{ .File.Path }}" class="button issue">{{ T "main_edit_this_page" }}</a>
+    {{ if .File }}<a href="https://github.com/kubernetes/website/edit/master/content/{{ site.Language.Lang }}/{{ .File.Path }}" class="button issue">{{ T "main_edit_this_page" }}</a>{{ end }}
     {{ end }}
   </div>
   {{ if and (not .Params.showcommit) $.GitInfo }}