fix: add Dragonfly compatibility for Lua scripts

[vyavdoshenko]

Adds compatibility with Dragonfly - a Redis-compatible in-memory store.

Problem: Undeclared keys in Lua scripts

Dragonfly requires all keys accessed in Lua scripts to be declared upfront in the KEYS array, or the script must explicitly opt out using the --!df flags=allow-undeclared-keys directive.

Cacheops dynamically generates conjunction keys (conj:*) inside Lua scripts, which causes failures in Dragonfly without this flag.

Related Dragonfly issues:

• Dragonfly does not allow accessing undeclared keys in lua scripts dragonflydb/dragonfly#272
• simplify lua_undeclared_keys_shas management dragonflydb/dragonfly#6119
• chore: more fixes for django-cacheops compatibility dragonflydb/dragonfly#6129

Solution:

Added --!df flags=allow-undeclared-keys directive to all Lua scripts. This directive is a Lua comment, so it's safely ignored by Redis.

Tested with Redis 4.x and Redis 7.x - all tests pass.