refactor: image handling logic + support for external images (#1235)

* refactor: simplify image partial logic, remove generation of different image sizes

* Remove `defaultImage.opengraph` configuration from `params.toml`.

layouts/page/search.json

@@ -6,8 +6,8 @@
 {{- range $filtered -}}
     {{- $data := dict "title" .Title "date" .Date "permalink" .RelPermalink "content" (.Plain) -}}
 
-    {{- $image := partialCached "helper/image" (dict "Context" . "Type" "articleList") .RelPermalink "articleList" -}}
-    {{- if $image.exists -}}
+    {{- $image := partial "helper/image" (dict "Image" .Params.image "Resources" .Resources) -}}
+    {{- if $image -}}
         {{- $imagePermalink := "" -}}
         {{- if and $image.resource (default true .Page.Site.Params.imageProcessing.cover.enabled) -}}
             {{- $thumbnail := $image.resource.Fill "120x120" -}}