FEATURE: Add group and category restrictions to house ads (#205)

# Description

This PR adds the ability to apply **group** and **category** restrictions to a **house ad**.

# What is included
- In order to get the group and category selectors to work within `admin/assets/javascripts/discourse/controllers/admin-plugins-house-ads-show.js` I needed to modernize the file. 
- I dropped the `bufferedProperty` implementation in favor of a vanilla ember approach
- I added `category_ids` and `group_ids` to our house ads model
- I added tests for group / category restrictions
- I added a preview button to display the house ad
- `/site.json` would return a object called `house_creatives` and a list of key value pairs that matched the ad name with the html, like so:
```js
{ AD_KEY: ad.html }
```
I need access to the category ids on the client to conditionally render the house ads so the new format will be: 
```js
{ AD_KEY: { html: ad.html, category_ids: ad.category_ids } }
```

# Screenshots
<img width="658" alt="Screenshot 2024-04-08 at 2 39 22 PM" src="https://github.com/discourse/discourse-adplugin/assets/50783505/b44b386d-65a1-4a2a-a487-d735b13357dd">

# Preview Video

https://github.com/discourse/discourse-adplugin/assets/50783505/6d0d8253-afef-4e15-b6fc-c6f696efd169

admin/assets/javascripts/discourse/routes/admin-plugins-house-ads-show.js

@@ -1,20 +1,22 @@
-import EmberObject from "@ember/object";
+import { TrackedObject } from "@ember-compat/tracked-built-ins";
 import DiscourseRoute from "discourse/routes/discourse";
 import I18n from "I18n";
 
 export default DiscourseRoute.extend({
   model(params) {
     if (params.ad_id === "new") {
-      return EmberObject.create({
+      return new TrackedObject({
         name: I18n.t("admin.adplugin.house_ads.new_name"),
         html: "",
         visible_to_logged_in_users: true,
         visible_to_anons: true,
       });
     } else {
-      return this.modelFor("adminPlugins.houseAds").findBy(
-        "id",
-        parseInt(params.ad_id, 10)
+      return new TrackedObject(
+        this.modelFor("adminPlugins.houseAds").findBy(
+          "id",
+          parseInt(params.ad_id, 10)
+        )
       );
     }
   },