PIP-36: Implement Block Info Publisher

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Description:

Implement the Raw Block Publisher, which will handle notifications related to raw block data.
This publisher should implement the Publisher interface and handle sending raw block data as per the PIP-36 specifications.

Tasks:

• Implement BlockInfoPublisher struct under www/zmq
• Ensure it correctly implements the Publisher interface
• Add functionality for sending raw block data notifications
• Write unit tests to ensure the publisher behaves as expected