Fix/issue 3311

[aartisonigra]

Fixes #3311

This change resolves a sharded Pub/Sub resubscription issue during in-place slot migrations in Redis Cluster.

Changes
Align sharded Pub/Sub migration event handling.
Ensure resubscribe and rediscover logic is triggered when a sharded channel is moved.
Fix typo in the emitted error event name:
sharded-shannel-moved-error → sharded-channel-moved-error

---

Note

Medium Risk
Cluster sharded Pub/Sub migration touches live subscription behavior during topology changes; the RediSearch change alters wire format for PARAMS and could affect any caller relying on the previous (incorrect) length.

Overview
Fixes cluster sharded Pub/Sub when slots move in place: the command queue callback now emits server-sunsubscribe in addition to sharded-channel-moved, so cluster node clients run rediscover → reattach listeners on the new master. Cluster slot setup registers that handler explicitly and corrects the failure event name to sharded-channel-moved-error.

Separately, FT.SEARCH PARAMS encoding is fixed: the length field is the number of key/value pairs (not total arguments), so parameterized queries like @field:"$x" bind correctly on Redis Stack/FT.

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