Add support for dynamic state syncing to the sync client

[powerslider]

Summary

Goal

• Extend the current static state sync to a dynamic model where sync targets can change during synchronization and block execution continues after finalization with a controlled queue.

Key ideas

• Start all syncers concurrently and independently.
• Allow UpdateSyncTarget to advance the sync target while syncers are running.
• Disallow further target updates once all syncers reach a consistent target.
• Finalize VM state (blockchain, atomic, shared memory, indices) before any post-finalization block execution.
• Buffer blocks that arrive during dynamic sync in a BlockQueue and execute them after finalization, with batching and race-safe cut-offs.
• Drive behavior with a clear state machine to handle edge cases and consistency

Non-goals

• No changes to consensus rules or block validation semantics.
• No redesign of underlying syncers’ low-level protocols - we adapt them via an interface for dynamic target updates.