Description
The current implementation of Transaction.to_bytes() and Transaction.from_bytes() only properly serializes and restores a single node transaction, even when the transaction itself contains multiple node IDs internally.

As a result:

• Transactions frozen with multiple node IDs lose information after to_bytes()
• from_bytes() cannot correctly restore all node contexts

Proposed Solution

• Update Transaction.to_bytes() to serialize each transactions for node_ids using the protobuf TransactionList type instead of serializing only a single Transaction.
• Similarly, update Transaction.from_bytes() to parse the TransactionList and reconstruct all node-specific transaction bodies.

Additional Notes

Potential considerations for the implementation:

• Preserve backward compatibility with previously serialized single-transaction bytes if possible
• Ensure signatures remain associated with the correct node-specific body bytes
• Ensure chunked transactions continue working correctly