Performance: Inbox Paging / loading (#11157)

* load messages per conversation

* only sort ones in ui

*  add contributor to message

* fix correct message layout/message

* mugenScroll on chatMessages

* fix lint, no mugen-scroll, use own scroll handler

* fix height / margin of modal + use button to load more

* fix tests

* user data from inbox

* style "load earlier messages"

*  move mapMessage to the inbox api result / extract sentMessage of members-api-controller

* fix test back

* fix test

* keep last scroll position

* just set the Id of the returned message instead of all other properties

* fix add new messages (buttons were hidden) + load more

* item-mounted debounce to trigger the re-scrolling

website/client/components/chat/chatCard.vue

@@ -273,5 +273,8 @@ export default {
       return habiticaMarkdown.render(String(text));
     },
   },
+  mounted () {
+    this.$emit('item-mounted', this.msg.id);
+  },
 };
 </script>