Carmine: modern core

[ptaoussanis]

Task: Modernize Carmine's core implementation.

Motivation: Carmine's implementation targets the older Redis RESPv2 API, and could do with a modern refresh for improved performance, documentation, usability, etc.

This is a big task, but I've already laid a fair bit of the groundwork.

If this is of popular interest, I can prioritise finishing this up and getting it out the door.

Prerequisite for: Redis Sentinel, Redis Cluster support.