Consider protobuf

[benedikt-bartscher]

Introduce a protobuf based protocol for websocket communication.
This is useful to differentiate messages sent over the wire in a type-safe and performant way.
buf could be used to streamline the js and python code generation.
Could be used to differentiate var types f.e. for #3732 and #3340

A first implementation could mostly rely on json strings or protobuf structs.
Because reflex already knows var types at compile time, we could later add a feature to dynamically create a protobuf spec for a computed var like this:

class State(rx.State):
  @rx.var(protobuf=True)
  def proto_int(self) -> int:
      return 5

Protobuf could also be interesting for StateManagerRedis.