FEATURE: Show 'marked solved by' in OP when topic is solved (#343)

Depends on: https://github.com/discourse/discourse-solved/pull/342

This feature adds the "Marked solved as" information to the solved post appended to OP.

Originally, I had moved the widget usage to a [component](https://github.com/discourse/discourse-solved/blob/39baa0be4a889fdbff108e887a677d9a298d27d4/assets/javascripts/discourse/components/solved-post.gjs), but due to "cooking quotes", after some internal discussion (t/95318/25) we will stick to widgets for now as the post-stream gets modernized.

test/javascripts/helpers/discourse-solved-helpers.js

@@ -199,6 +199,12 @@ export const postStreamWithAcceptedAnswerExcerpt = (excerpt) => {
     featured_link: null,
     topic_timer: null,
     message_bus_last_id: 0,
-    accepted_answer: { post_number: 2, username: "kzh", excerpt },
+    accepted_answer: {
+      post_number: 2,
+      username: "kzh",
+      excerpt,
+      accepter_username: "tomtom",
+      accepter_name: "Tomtom",
+    },
   };
 };