Optimize increment and decrement for RedisCacheStore

[fatkodima]

Before this PR, when incrementing/decrementing a counter with :expires_in option, we will make 3 requests to Redis.

increment/decrement, for example, is very heavily used by rack-attack - https://github.com/rack/rack-attack/blob/95ce9fdd7c99a527a46ffc477b01e682fed48dce/lib/rack/attack/store_proxy/redis_cache_store_proxy.rb#L13-L25 (that implementation currently also makes redundant calls and works around unsupported expires_in in older versions; the implementation should just use the native implementation from rails in the future). Increment can be called several times per request (for each throttling rule).

With this PR, we will make only 1 pipelined request, if possible.

cc @byroot

[casperisfine]

@fatkodima thanks for the PR, and I'm in favor of this improvement, however I'm afraid there's a bit too much unrelated and not strictly necessary changes. Not saying they're not desirable, but it would make it much easier if this PR was really only focused on the pipelining change.

The state of the code makes me think we should really refactor all this so that Redis::Distributed / Redis::Cluster support doesn't make the code as unwidely, but I think it's best done in a dedicated PR.

[fatkodima]

@byroot Thanks for the review. Agreed. That changes were left from my original implementation, now they are not needed.
Updated to include only the relevant changes.

[fatkodima]

@byroot Rebased on top of the refactoring with the #45711 (comment) suggestion. Let me know if some other changes needed.