feat(ai): add chunk formatting capabilities

[palmer-cl]

Adds real-time formatting to editor coming from streaming API

• adds formatRegistry that can be extended to all format types, currently starts with bold text as that is the only current contract set by insights endpoint API as **_____**
• Updates handleChunk to format document
• Format document function seeks to optimistically find match in one node, and if that fails, formats across nodes
• Updates HandleDone function to wait for any pending formats to be completed, and calls format one single time to account for the last node being rendered

[palmer-cl]

@harbournick this can be combined with #501 or kept separate

[harbournick]

LGTM