Add support of IFEQ/IFNE/IFDEQ/IFDNE in SET command

[PragmaTwice]

https://redis.io/docs/latest/commands/set/.

Depends on #3309.

[ShockleysxX]

Hi, @PragmaTwice, I'm new here, may I try working on this issue as my first task to kvrocks community!

[PragmaTwice]

Sure! Assigned.

[kirito632]

Hi, I've submitted a PR #3393 implementing this feature. Could someone please take a look? Thanks!