Issue #3512245 by grimreaper: Prop source to get background URL

Closes #3512245

config/schema/ui_patterns_settings.sources.schema.yml

@@ -8,3 +8,14 @@ ui_patterns_source.media:
       mapping:
         media_library_selection:
           type: string
+
+ui_patterns_source.media_image_url:
+  type: mapping
+  label: 'Source: Media image URL'
+  mapping:
+    media:
+      type: string
+      label: 'Media ID'
+    image_style:
+      type: string
+      label: 'Image style'