Message queue cleanup

[FUDCo]

Since we stopped handling location hints as a parameter to sendRemoteMessage, the message queue element was reduced to an object holding a single string property, which is silly. This PR changes it to just a string.

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Note

Replaces QueuedMessage objects with raw string messages across the queue and network code, adjusting APIs, logging, and tests.

• Remotes/Queue:
  • Refactor MessageQueue to store raw string messages (remove QueuedMessage).
  • Update methods: enqueue, dequeue, dequeueAll, messages getter, and replaceAll to use string types.
• Remotes/Network:
  • Adjust queue handling in flushQueuedMessages to process string messages and update logging/serialization (fromString).
  • Rename receiveMsg to receiveMessage and update call sites.
• Tests:
  • Update MessageQueue.test.ts and network.test.ts mocks/expectations to use plain strings.

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[grypez]

LGTM