The problem/use-case that the feature addresses

Mostly to allow external tools to perform a consistency check between servers (e.g. master and replica)
The issue is that when sampling server A some key may exist but when checking server B it might already be logically expired, thus causing the consistency check to fail

Description of the feature

A debug subcommand/config that tells Redis to ignore all TTLs (i.e. completely turn off lazy/active expiry)