feat: new archives layout (#989)

* feat(archives): add search bar to archives page

* fix: error `file is nil; wrap it in if or with` from Hugo 0.123.0

* style: rename `search.ts` to `archives.ts`

* refactor: remove `search` page layout

* doc: remove `search` from `exampleSite`

* fix: generate JSON output for archives page in exampleSite

* feat: put archives search form under categories list

layouts/_default/archives.json

@@ -0,0 +1,13 @@
+{{- $pages := where .Site.RegularPages "Type" "in" .Site.Params.mainSections -}}
+{{- $result := slice -}}
+
+{{- range $pages -}}
+    {{- $data := dict 
+        "title" .Title
+        "content" (.Plain)
+        "id" .File.UniqueID
+    -}}
+    {{- $result = $result | append $data -}}
+{{- end -}}
+
+{{ jsonify $result }}