Make ERC1155 Transfer Data Field Optional

[0xFirekeeper]

PR-Codex overview

This PR modifies the ThirdwebExtensions.cs file to set default values for the data parameter in two methods, ensuring that if data is not provided, an empty byte array is used instead. This change enhances the robustness of the methods by preventing potential null reference issues.

Detailed summary

• In the method signature for ERC1155_SafeTransferFrom, changed byte[] data to byte[] data = null.
• Updated the method to use data ?? Array.Empty<byte>() instead of data when calling ThirdwebContract.Write.
• In the method signature for ERC1155_SafeBatchTransferFrom, changed byte[] data to byte[] data = null.
• Updated the method to use data ?? Array.Empty<byte>() instead of data when calling ThirdwebContract.Write.

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