refactor(protocols): remove sync module and clean up protocol exports

- Deleted the sync module, which provided synchronization protocol extensions and state management.
- Updated the protocols module to remove references to the sync module, streamlining the codebase.
- This change simplifies the network protocols by focusing on the request-response functionality.

Author: michaelgpt

app/src/actors_v2/network/protocols/mod.rs

@@ -1,5 +1,3 @@
 pub mod request_response;
-pub mod sync;
 
 pub use request_response::{BlockCodec, BlockProtocol, BlockRequest, BlockResponse};
-pub use sync::{PeerSyncInfo, SyncState, MAX_BLOCKS_PER_REQUEST};