1.19.1 support

[JLyne]

Adds support for 1.19.1. The highlights:

• Updated packets and data packs for 1.19.1
• Added some buffer helper methods for un/packing player public keys and 1.19.1 signed chat messages. A SignedMessage object has also been added for easier management of all the components of a signed chat message
• The signature sent on login changed between 1.19 and 1.19.1. Both versions are now supported by quarry servers.
• Server login handling has been updated to more closely match vanilla server logic for 1.19+
• The client can optionally send a UUID alongside the signature during the login process. Neither of these are currently sent by quarry clients, but this could be implemented in the future.
• Examples have been updated for 1.19.1. For simplicity none of them attempt to verify signed messages, and the chat room example now uses system messages for 1.19+ clients.
• An "advanced" chat room example has been added which attempts to handle signed messages in the same way as a vanilla server.

[JLyne]

Ready for review now. Needs a fair bit of testing as there's a lot going on with chat signing etc.