refs https://github.com/TryGhost/Ghost/issues/9724
- add `registerComponent` hook to cards so that `{{koenig-editor}}` can fetch properties from card components directly
- add word count and reading time utilities
- add throttled word count update routine to `{{koenig-editor}}` that walks all sections and counts text words or fetches word/image counts from card components
- add `wordCountDidChange` hook to `{{koenig-editor}}` so that word count + reading time can be exposed
- modify editor controller to update it's own word count property when koenig triggers it's action
- modified the editor template to show reading time + word count next to the post status
