RESP3 support

[q0w]

Hi, to use client-side caching, resp3 should be used, but fakeredis is failing with

redis.exceptions.ResponseError: unknown command `hello`, with args beginning with:

I see that hello command is not implemented

fakeredis-py/docs/supported-commands/Redis/CONNECTION.md

Line 95 in 0ad44e8

#### [HELLO](https://redis.io/commands/hello/) <small>(not implemented)</small>

but how much work is required to support resp3?

[cunla]

Implementing hello command is one thing - That should be relatively easy (the proto for the client can be "ignored").

Support for RESP3 is another thing - that would be more challenging.
Let me see whether I can design it. Would you like to participate in implementing this?

[q0w]

I am not sure where to start. I have not seen yet how fakeredis works.