Use EmojiDialog popup in chatbar

This converts the emoji dialog in the chatbar to be the same popup as for reactions. This includes:

- EmojiPicker and ReactionPicker were already similar and are made identical, as such ReactionPicker no longer needed
- Emoji dialog used for both reactions and chatbar emojis
- Add some parameters to allow for different use cases (include custom emojis and whether selection closes the popup)

![image](/uploads/c71bb5ffdc6914efad654998a886ade6/image.png)