Use RedisJSON to store json objects

Hello, Currently, keyv use [json-buffer](https://github.com/jaredwray/keyv/tree/main/packages/keyv#custom-serializers) as default serializer/deserialize. We store everything as a string. These are **high consuming cpu functions**, and when the main goal is to be fast, this is not ideal. Redis has a native way to store json objects, using [RedisJSON](https://developer.redis.com/howtos/redisjson/using-nodejs/). This is not enabled by default, but is not so difficult to enable it. Anyway, the @keyv/redis lib is [not using this api](https://github.com/microlinkhq/keyvhq/blob/master/packages/redis/src/index.js#L42), which in understandable, but would be great to support it, optionally. What can be done to add RedisJSON support to keyv ecosystem ?