refs https://github.com/TryGhost/Ghost/issues/9724
- the "paste url on a selection to make it a link" feature from the main editor was missing in caption inputs
- copied functionality across (shared functionality needs extracting at some point)
refs https://github.com/TryGhost/Ghost/issues/9724
- added `{{koenig-basic-html-input}}` component
- uses a stripped down version of Koenig
- supports all inline formatting that Koenig supports
- supports inline text expansions
- supports inline key commands
- limited to a single paragraph
- serialises and deserialises from HTML rather than mobiledoc
- updated `{{koenig-caption-input}}` to use `{{koenig-basic-html-input}}`
- updated image and embed cards to calculate word counts correctly for html captions
- bumped Spirit dependency to fix styling of toolbars within the editor canvas
- fixed positioning in toolbar components to account for `parentElement` not necessarily being the closest element to position against
