feat: Implement synchronizer logic as servers

[elementbound]

This is an experimental PR, that refactors much of netfox's internals, inspired by Godot's server pattern.

While Godot had its own requirements, the interpretation here is that:

• Servers are singletons that provide access to a group of related functionalities
• Servers act as an interface, similar to a facade, as an outer boundary to internal details
• Nodes act as convenient wrappers to servers, meaning they expose some config and then do some server calls based on said config

Hopefully this allows:

• Simplified history tracking
• Greatly simplified RollbackSynchronizer, StateSynchronizer, and PredictiveSynchronizer
• Easier testing
• Batching - sending state in one RPC per tick, instead of one RPC per RBS per tick
• Nested RBS's
• An easier fix for RollbackSynchronizer removes mutated states on rollback #383
• Buffering incoming data in case the target node doesn't exist yet, instead of printing errors
• Easier implementation of Rollback liveness #468

Also lays the foundations for some potentially wild features like:

• RPCs on objects
• Rollback on objects

TODO:

• Diff states
• Redundant inputs
• Binary state serialization
• Binary input serialization
• Support schemas
• Support visibility filtering
• Networked IDs
• Command bus
• StateSynchronizer
• PredictiveSynchronizer
• Update metrics
• Toggleable input broadcast
• Mutations?
• Separate into multiple PRs

Pending fixes:

• Input prediction
• Diff states

Sanity tasks:

• Implement tests
• Implement / postpone TODOs
• Test with large states, e.g. larger than the MTU of 1500 bytes
  • Large state ( 2k ) doesn't arrive consistently using noray + relay
  • Checking the same scene with 1.35.3 works well
• Test physics stepping
• Test display offset and input delay
• Test Track and expose latest confirmed tick #470
• Test all examples

Introduces #556
Closes #559
Closes #432

[Archists-dev]

Great stuff!!