Feature Request: Add HEXPIRE Command

[dwprz]

I would like to request the addition of a HEXPIPRE command to the ioredis library. The HEXPIPRE command would allow users to set an expiration time on individual fields within a hash, similar to how the EXPIRE command sets an expiration time on keys. This feature would be particularly useful for scenarios where certain fields within a hash need to expire independently of the hash itself.

Consider an order management system where each user's orders are stored as a hash with multiple fields representing different orders. Each order needs to have its own expiration time to ensure that old or unfulfilled orders are automatically removed after a certain period. The HEXPIPRE command would allow us to set an expiration time on each order field without affecting other orders or the main hash.