[NEW] Add DELEX key IFEQ ifeq-value as an alias for DELIFEQ

The problem/use-case that the feature addresses

This would made the Valkey at least partially compatible with Redis. (Partially because Redis under DELEX also implements IFNE, IFDEQ, IFDNE along with IFEQ)

Description of the feature

DELEX key IFEQ ifeq-value is an alias for DELIFEQ key value