Switch from automerge to loro

[rroohhh]

Loro has multiple advantages over automerge

• comes with python bindings, so we don't have to maintain our own
• has a native undo / redo mechanism
• has a native awareness / presence mechanism
• has native cursor / selection tracking
• has a mechanism to subscribe to changes of a sub container (map / list / etc) (could be used to optimize the useDocumentSelector stuff)

Right now basic text editing and undo redo works, backend / worker integration is completely missing.
I test it by manually converting a automerge doc to a loro doc using the conv_loro.py script and overriding the document data with admin set_document.

TODO:

• worker integration
• periodic change -> snapshot encoding rollups
• awareness
• fix everything around speaker names
• tests for the LoroEventBatch -> slate Transform conversion. (just capture an editing trace and play it back maybe?)
• migration from automerge -> loro documents
• remove docProxy
• types lol
• move the slate <-> loro stuff to a seperate repo like slate <-> automerge?
• use useSyncExternalStore