Fix typos in HTML target attributes

In some places, we were using `blank` instead of `_blank`. Most browsers
treat `blank` like `_blank`, though, so most people didn't experience
any difference.

In another place, we were incorrectly passing the `target` option inside
an `options:` hash, resulting in invalid HTML.

app/components/admin/site_customization/pages/index_component.html.erb

@@ -34,7 +34,7 @@
               <%= actions.action(:show,
                                  text: t("admin.site_customization.pages.index.see_page"),
                                  path: page.url,
-                                 options: { target: "_blank" }) %>
+                                 target: "_blank") %>
             <% end %>
           <% end %>
         </td>