Introduce MediaContainer class to ease combining media definitions

wagtail/admin/ui/components.py

@@ -1,6 +1,6 @@
 from typing import Any, MutableMapping
 
-from django.forms import MediaDefiningClass
+from django.forms import Media, MediaDefiningClass
 from django.template import Context
 from django.template.loader import get_template
 
@@ -20,3 +20,17 @@ class Component(metaclass=MediaDefiningClass):
 
         template = get_template(self.template_name)
         return template.render(context_data)
+
+
+class MediaContainer(list):
+    """
+    A list that provides a ``media`` property that combines the media definitions
+    of its members.
+    """
+
+    @property
+    def media(self):
+        media = Media()
+        for item in self:
+            media += item.media
+        return media