[NEW] Add HEXPIRE and new features in 7.4

[tobiasBora]

The problem/use-case that the feature addresses

Redis 7.4 introduces notably HEXPIRE, that extend EXPIRE to individual keys of a hash function. This is quite practical for many reasons, for instance I use it to count the number of connected users on each server, and the HEXPIRE allows me to remove keys when the server has been offline for too long (e.g. due to a crash).

More generally, here are the new commands introduced in 7.4, from https://raw.githubusercontent.com/redis/redis/7.4/00-RELEASENOTES:

• HEXPIRE and HPEXPIRE set the remaining time to live for specific fields
• HEXPIREAT and HPEXPIREAT set the expiration time to a UNIX timestamp for specific fields
• HPERSIST removes the expiration for specific fields
• HEXPIRETIME and HPEXPIRETIME get the expiration time for specific fields
• HTTL and HPTTL get the remaining time to live for specific fields

Description of the feature

Same as in https://redis.io/docs/latest/commands/hexpire/

Alternatives you've considered

Creating keys for each item… but then it is hard to keep track of them all, as KEYS is not recommended in production: https://stackoverflow.com/questions/30728973/redis-get-all-keys-values-from-redis-with-prefix

[zuiderkwast]

Yes, see also #640. We want to add this but it's not trivial.

If or when we add it, we should use the same commands as redis.

[PingXie]

Let's continue the discussion on #640.