Registration of push message listeners

[mp911de]

We should allow registration of push message listeners given that Redis 6 (RESP3) features push messages. In RESP3 mode, a connection does not require an active subscription to receive push notifications, instead, Redis sends messages starting with > where the first item is a String. The rest of the message remains dynamic.

It would make sense to provide a generic callback such as RedisPushListener with a onPush(String type, Object args) signature. Examples for push messages are:

Pub/Sub Channel Subscription:

>3
$7
message
$5
hello
$5
world

Client-side Caching:

>3
>2
$10
invalidate
*1
$3
key

Typically, the second argument (Object) would be either a List<Object> containing the all arguments from position 2 or be only the second argument.

Since we don't have any relation to keys and values, we need to define which part of a RedisCodec we would have to use.

Push message listeners would be registered directly on StatefulConnection. For Redis Cluster, we could add an extension similar to RedisClusterPubSubListener that defines the cluster node from which the event originated.