Implement WebSockets protocol binding

[slinkydeveloper]

I would love to look at implementing https://github.com/cloudevents/spec/blob/master/websockets-protocol-binding.md for one of our integrations (maybe actix?)

[nguyenquannnn]

Hey I would love to take a dig at this issue for Hactoberfest!

[slinkydeveloper]

Go ahead! I think we want to use actix-web for the protocol binding https://actix.rs/docs/websockets/, so you can just modify the cloudevents-sdk-actix-web crate adding the new stuff in there.

A first step is to implement the message serializer/deserializer for the websockets data structures. Then, we need to figure out the apis (we can do that in 2 PRs)

[nguyenquannnn]

Hey @slinkydeveloper, currently WIP, taking time since this domain is new to me :D But I want to ask, from the spec of websocket, are we supporting the binary frame streaming (avro event format)?

[slinkydeveloper]

@nguyenquannnn I think, for now, just the text format is fine, since this sdk just supports json conversion

[No9]

Added a reference web socket implementation to the tide example
a71f661
From what I can see in the spec the only requirement is to implement the upgrade headers but it would be great to get some feedback if someone thinks it can be improved.