Add a should_render.html partial

Encapsulates the decision making about whether a page should be rendered.

layouts/partials/page/first_section.list.html

@@ -25,7 +25,7 @@
     <section id="{{ .Date | time.Format "2006" }}" class="main__posts-by-year">
       <h2 class="main__section-heading">{{ .Title }}</h2>
       {{ range .RegularPagesRecursive.ByPublishDate.Reverse -}}
-        {{ if or (not .Draft) hugo.IsDevelopment -}}
+        {{ if partial "page/should_render.html" . -}}
           {{ .Render "page_summary" }}
         {{ end }}
       {{ end }}