FEATURE: New 'Reviewable' model to make reviewable items generic

Includes support for flags, reviewable users and queued posts, with REST API
backwards compatibility.

Co-Authored-By: romanrizzi <romanalejandro@gmail.com>
Co-Authored-By: jjaffeux <j.jaffeux@gmail.com>

app/assets/javascripts/admin/routes/admin-flags-index.js.es6

@@ -1,8 +0,0 @@
-export default Discourse.Route.extend({
-  redirect() {
-    let segment = this.siteSettings.flags_default_topics
-      ? "topics"
-      : "postsActive";
-    this.replaceWith(`adminFlags.${segment}`);
-  }
-});

app/assets/javascripts/admin/routes/admin-flags-topics-show.js.es6

@@ -1,20 +0,0 @@
-import { loadTopicView } from "discourse/models/topic";
-
-export default Ember.Route.extend({
-  model(params) {
-    let topicRecord = this.store.createRecord("topic", { id: params.id });
-    let topic = loadTopicView(topicRecord).then(() => topicRecord);
-
-    return Ember.RSVP.hash({
-      topic,
-      flaggedPosts: this.store.findAll("flagged-post", {
-        filter: "active",
-        topic_id: params.id
-      })
-    });
-  },
-
-  setupController(controller, hash) {
-    controller.setProperties(hash);
-  }
-});

app/assets/javascripts/admin/routes/admin-route-map.js.es6

@@ -120,18 +120,6 @@ export default function() {
       }
     );
 
-    this.route(
-      "adminFlags",
-      { path: "/flags", resetNamespace: true },
-      function() {
-        this.route("postsActive", { path: "active" });
-        this.route("postsOld", { path: "old" });
-        this.route("topics", { path: "topics" }, function() {
-          this.route("show", { path: ":id" });
-        });
-      }
-    );
-
     this.route(
       "adminLogs",
       { path: "/logs", resetNamespace: true },