Hooked up event aware cache wrapper to posts cache

refs https://github.com/TryGhost/Toolbox/issues/522

- When caching responses the posts cache can create a situation where it becomes stale within the TTL period and would give stale responses to shared caches.
- Having full cache reset on 'site.changed' event makes cached content evergreen reducing the risk of caching stale content in shared caches

ghost/core/core/server/services/posts-public/service.js

@@ -9,6 +9,8 @@ class PostsPublicServiceWrapper {
         const {Post} = require('../../models');
         const adapterManager = require('../adapter-manager');
         const config = require('../../../shared/config');
+        const EventAwareCacheWrapper = require('@tryghost/event-aware-cache-wrapper');
+        const EventRegistry = require('../../lib/common/events');
 
         let postsCache;
         if (config.get('hostSettings:postsPublicCache:enabled')) {

ghost/core/package.json

@@ -82,6 +82,7 @@
     "@tryghost/email-service": "0.0.0",
     "@tryghost/email-suppression-list": "0.0.0",
     "@tryghost/errors": "1.2.21",
+    "@tryghost/event-aware-cache-wrapper": "0.0.0",
     "@tryghost/express-dynamic-redirects": "0.0.0",
     "@tryghost/helpers": "1.1.75",
     "@tryghost/html-to-plaintext": "0.0.0",