refactor: migrate page visibility control from Params.hidden to the new build.list parameter. (#1249)

* refactor: migrate page visibility control from `Params.hidden` to the new `build.list` parameter.

* Rename rss.xml to home.rss.xml

layouts/page/search.json

@@ -1,9 +1,7 @@
 {{- $pages := where .Site.RegularPages "Type" "in" .Site.Params.mainSections -}}
-{{- $filtered := where $pages "Params.hidden" "!=" true -}}
-
 {{- $result := slice -}}
 
-{{- range $filtered -}}
+{{- range $pages -}}
     {{- $data := dict "title" .Title "date" .Date "permalink" .RelPermalink "content" (.Plain) -}}
 
     {{- $image := partial "helper/image" (dict "Image" .Params.image "Resources" .Resources) -}}