**Is your feature request related to a problem? Please describe.** N/A **Describe the solution you'd like** Kraken Spot Websockets (v2) supports level 3 market-by-order data. Support `L3_BOOK` for exchange `Kraken` in cryptofeed. **Describe alternatives you've considered** N/A **Additional context** - https://docs.kraken.com/api/docs/websocket-v2/level3 - https://docs.kraken.com/api/docs/guides/spot-ws-l3-v2