Option to use Redis 7.4 hash field TTL for presence

[FZambia]

Proposed changes

Redis 7.4 added per HASH field TTL. Here we use it for presence information by adding new boolean option redis_presence_hash_field_ttl. Benefits:

• less memory in Redis for presence information since less data to keep (no need in separate ZSET), up to 1.6x improvement.
• slightly better CPU utilization on Redis side since less keys to deal with in LUA scripts during presence get, add, remove operations.

This PR uses an option in Centrifuge introduced in centrifugal/centrifuge#403

By default, Centrifugo will continue using the current presence implementation with ZSET since the new option only works with Redis >= 7.4 and requires explicit intent to be used.