Port CRDT key expiry from akka-core #31721

[pjfanning]

Ports the CRDT key expiry feature from akka/akka-core#31721 with imports updated for Pekko. Allows Replicator entries to be automatically removed (without tombstones) after a configurable period of inactivity.

part of #2730

Configuration

pekko.cluster.distributed-data.expire-keys-after-inactivity {
  "session-*" = 30 minutes
  "cache-key" = 5 minutes
}

Prefix wildcard (*) matching supported.

Changes

Classic API (distributed-data)

• New Expired[A] subscribe response (alongside Changed/Deleted) sent to subscribers when a key is evicted
• ReplicatorSettings gains expiryKeys: Map[KeyId, FiniteDuration] with backward-compat constructor, withExpiryKeys() Scala/Java API, and parseExpiry() helper
• dataEntries extended from (DataEnvelope, Digest) to (DataEnvelope, Digest, Timestamp) to track last-used time per key
• Timestamp updated on receiveGet, receiveUpdate, receiveDelete
• cleanupExpired() runs on every gossip tick; expired entries removed and subscribers notified
• Gossip protocol (Status/Gossip messages) now carries usedTimestamp so all replicas share expiry clock state — entries received via gossip that are already expired are discarded

Durable store

• New Expire(keys: Set[KeyId]) message added to DurableStore protocol
• LmdbDurableStore handles Expire via new dbDelete(keys) method

Serialization

• ReplicatorMessages.proto: optional sint64 usedTimestamp = 3 added to Status.Entry and Gossip.Entry
• Generated ReplicatorMessages.java updated accordingly (zero value = unset; backward-compatible)
• ReplicatorMessageSerializer updated to read/write timestamps

Typed API (cluster-typed)

• Expired[A] type alias added to scaladsl.Replicator
• Expired[A] case class added to javadsl.Replicator
• ReplicatorBehavior forwards classic Expired to Java API subscribers

[He-Pin]

Should we wait this on 3.17？

[pjfanning]

March 16 (today) is ok - https://github.com/akka/akka-core/blob/v2.8.0/LICENSE