Add redis-streams backend

[alex-oleshkevich]

Based on #102
Seems that the author of #102 did not notice a call for update, so I am creating a new PR in order to proceed with this backend.

@encode/maintainers please do a review

closes #102
closes #3

[tomchristie]

🤔

[alex-oleshkevich]

This is What's next section. Redis Streams lands with this PR and Kafka is already there.

[tomchristie]

Are you able to give a brief pointer towards when there'd be a use-case for redis streams vs. redis pub/sub?

(Just in this conversation is enough, I don't think we have sufficient docs to have a good place for this right now)

[alex-oleshkevich]

Redis Streams is a lightweight Kafka alternative. While pub sub is fire-and-forget, Redis stream is an append only log.

[tomchristie]

Reviews README and discovers that past me already wrote about this. Thanks that person.

To be more capable we'd really want to [...]

Add support for subscribe('chatroom', history=100) for backends which provide persistence. (Redis Streams, Apache Kafka) This will allow applications to subscribe to channel updates, while also being given an initial window onto the most recent events. We might also want to support some basic paging operations, to allow applications to scan back in the event history.

[tomchristie]

👍🏼

[tsotnesharvadze]

thanks 🙏