Fix incompatibility for HSETEX command

[BorysTheDev]

HSETEX was implemented in Dragonfly before it was added to Redis, so we have a completely different layout.
We can support our format and Redis format simultaneously, because Redis uses tags like KEEPTTL, FIELDS, EXAT etc, but we don't. If such tags exist in the command format, we can understand that it is Redis approach.
I think we should proceed to support our format too, because I saw reports with bugs from some users regarding this functionality.