DEV: Modernize + adopt PostList component (#139)

This update makes use of core's new `PostList` component (discourse/discourse#30604) to show the follow post feed. Additionally, it modernizes the route/controller around calling this component to make use of `RouteTemplate` instead of a route, template, and controller.

Tests already exist, but we update classes used in the test to be more fitting for the new component.

Author: keegangeorge

assets/javascripts/discourse/components/follow-feed-post.hbs

@@ -0,0 +1,49 @@
+import Component from "@glimmer/component";
+import { action } from "@ember/object";
+import { service } from "@ember/service";
+import RouteTemplate from "ember-route-template";
+import PostList from "discourse/components/post-list";
+import { i18n } from "discourse-i18n";
+
+export default RouteTemplate(
+  class extends Component {
+    @service currentUser;
+
+    get viewingSelf() {
+      return this.args.model.user.id === this.currentUser.id;
+    }
+
+    @action
+    async loadMore() {
+      if (!this.args.model.canLoadMore) {
+        return [];
+      }
+
+      await this.args.model.findItems();
+
+      return this.args.model.content;
+    }
+
+    <template>
+      {{#if @model.noContent}}
+        {{#if this.viewingSelf}}
+          <div class="alert alert-info">{{i18n
+              "user.feed.empty_feed_you"
+            }}</div>
+        {{else}}
+          <div class="alert alert-info">
+            {{i18n "user.feed.empty_feed_other" username=@model.user.username}}
+          </div>
+        {{/if}}
+      {{else}}
+        <PostList
+          @urlPath="postUrl"
+          @posts={{@model.content}}
+          @fetchMorePosts={{this.loadMore}}
+          @additionalItemClasses="follow-stream-item"
+          class="follow-stream"
+        />
+      {{/if}}
+    </template>
+  }
+);

assets/javascripts/discourse/components/follow-feed-post.js

@@ -158,7 +158,7 @@ acceptance("Discourse Follow - Follow Posts Feed", function (needs) {
 
   test("posts are shown", async (assert) => {
     await visit("/u/eviltrout/follow/feed");
-    const posts = queryAll(".user-follows-tab .user-stream-item");
+    const posts = queryAll(".follow-stream .follow-stream-item");
     assert.equal(
       posts.length,
       3,
@@ -173,7 +173,7 @@ acceptance("Discourse Follow - Follow Posts Feed", function (needs) {
 
   test("long posts excerpt", async (assert) => {
     await visit("/u/eviltrout/follow/feed");
-    const posts = queryAll(".user-follows-tab .user-stream-item");
+    const posts = queryAll(".follow-stream .follow-stream-item");
     assert.ok(
       exists(posts[2].querySelector(".expand-item")),
       "long posts are first rendered collapsed"