refs https://github.com/TryGhost/Ghost/issues/9505
- use `ember-sticky-element` to stick card icons in top left when scrolling
- pass an `headerOffset` down from the `{{gh-editor}}` component through Koenig and the card components so that it can be used for adjustments where necessary
- calculate `headerHeight` in `{{gh-editor}}` any time we change the header class
refs https://github.com/TryGhost/Ghost/issues/9505
- add `autofocus` property to markdown editor component
- remove autofocus routine that was in place for old textarea based editor
refs https://github.com/TryGhost/Ghost/issues/9505
- use `{{gh-scroll-trigger}}` components at top and bottom of the markdown card when in edit mode so that styles can be applied to the `.editor-toolbar` element to keep the toolbar fixed at the bottom of the screen whilst scrolling
refs https://github.com/TryGhost/Ghost/issues/9505
- use Spirit classes for card context menu
- add button and icon class options for context menu items
- add ability to have icon+text for context menu items
- add "Edit" context menu item to markdown and html cards
refs https://github.com/TryGhost/Ghost/issues/9505
- add `deleteCard` action to `{{koenig-editor}}` component and pass it through to the component cards
- required modifying the `_deleteCard` behaviour so that it doesn't always try to move the cursor
- use `onLeaveEdit` action from `{{koenig-card}}` in the markdown and html cards to check if their payload is empty and remove the card when exiting edit mode
- fixed `onLeaveEdit` action firing when card first rendered
refs https://github.com/TryGhost/Ghost/issues/9311
- initial CSS for container card outline, selection state, toolbar, etc
- adds `{{#koenig-card}}` component to be used inside of component card templates to handle the default card container HTML, mouse interactions, etc
- update `{{koenig-card-markdown}}` to use the new `{{koenig-card}}` component
- add render/edit mode views
- focus the textarea when entering edit mode
- updated `{{koenig-editor}}`
- add <kbd>Cmd+Enter</kbd> command to put a selected card into edit mode
- when inserting new cards put them into edit mode immediately
- move edit/select methods out of actions and into normal methods so that timing is easier to reason about
- skip `cursorDidChange` process when cursor changes as a result of a card selection, fixes issues with `selectCard` being triggered multiple times unexpectedly
refs https://github.com/TryGhost/Ghost/issues/9311
- add `{{koenig-card-markdown}}` component that renders an auto expanding textarea with the markdown card value
- add `{{card-markdown}}` that is an alias of `{{koenig-card-markdown}}` for backwards compatibility - all of our pre-1.0 alpha cards and our current markdown implementation do not have the `koenig-` prefix in their card names
