[NEW] Add KeyDB's EXPIREMEMBER command

[binaryfire]

One of the main reasons we've been using KeyDB has been their EXPIREMEMBER command. See: https://docs.keydb.dev/blog/2021/06/08/blog-post/

Implementing tags in Redis is problematic because set members don't expire. The only solution is implementing complex application logic to remove expired keys from sets (otherwise you end up with a memory leak). And iterating over large datasets to perform the garbage collection isn't very performant.

EXPIREMEMBER solved all of this and was a real game changer. Unfortunately KeyDB isn't well maintained nowadays so we've finally decided to migrate our apps to Valkey. It would be great if the same command could be added to Valkey.

Also tagging @michael-grunder since I think you used to work on KeyDB?

[michael-grunder]

I think there are plans to add this functionality. You can find the discussion/progress at #640.