Trigger an `emojiSelected` event instead of manually calling `insertIntoTextArea` on the `converse-message-form` a component.
This loosens the coupling between the emoji picker and `converse-message-form`.
Call `disableArrowNavigation` when the emoji-picker is disconnected from
the DOM or when escape is pressed. See #2754
Had to make various other changes due to incompatibilities.
- Use the new `lit` package instead of `lit-html` or `lit-element`
- Drop `haunted` since it breaks the rules by specifying `type: module`
but then doesn't import with file extensions
- Use Sass Dart instead of node-sass (fixes#2445)
- Upgrade Karma