Added table of contents widget to article modal (#22008)

ref https://linear.app/ghost/issue/AP-634/table-of-contents-in-reader-view

- Adds a table of contents widget to the right side of articles in
reader view that let's you navigate between headings for easier
navigation in long, complex articles
- Enhanced popover component with configurable side positioning
- Updated package version to 0.3.44

apps/admin-x-activitypub/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@tryghost/admin-x-activitypub",
-  "version": "0.3.43",
+  "version": "0.3.44",
   "license": "MIT",
   "repository": {
     "type": "git",