fix(grc721): Make basic metadataNFT implementation usable from external packages

[stefann-01]

The current implementation of grc721_metadata.gno has a critical usability issue where external packages can't access basic_nft.gno methods when using NewNFTWithMetadata(). This is because:

1. The metadataNFT struct in grc721_metadata.gno embeds *basicNFT which is unexported
2. While embedding promotes methods within the same package, unexported methods are not accessible from external packages
3. External packages could only access the metadata-specific methods (SetTokenMetadata, TokenMetadata)

Changes made:

• Add forwarding methods in metadataNFT for all basicNFT functionality (Name, Symbol, BalanceOf, etc.)
• Remove owner check in SetTokenMetadata, since this is something that should be left for NFT collection creator to choose who should be able to use this method

These changes ensure that external packages can properly use the metadata NFT implementation with full NFT functionality while maintaining proper encapsulation of the underlying basicNFT struct interface.

An example of a working usage of this updated grc721_metadata.gno can be found in this file.

[Gno2D2]

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[notJoon]

I don't know why owner check were done in the existing code, but I think making access control looser as it has been modified now would allow for more flexible application to other projects in the future.

Still, this seems related to policy, we should check with others for their opinions as well. Anyway LGTM

[leohhhn]

Why did you remove this?

[stefann-01]

As described in the description, I removed the owner check in SetTokenMetadata. This change ensures that the decision of who can use this method is left to the NFT collection creator, rather than being predefined in the basic implementation.

In most cases, setting token metadata is typically a one-time operation, either automated by the contract or handled by the collection owner. Token owners usually do not have the capability to modify metadata.

By removing the owner check in the basic implementation, we allow greater flexibility, enabling both options.

[r3v4s]

• grc721 metadata is implementation of opensea metadata standards.
• opensea does supports ERC-7015 to proof ownership. (which is pretty latest spec)

---

Therefore, removing owner logic might be work for now but as what @leohhhn said about refactoring, we won't have this issue :D

[leohhhn]

Hopefully we'll do a full refactor of the GRC721 package and we won't have issues with this :)

[stefann-01]

Hopefully we'll do a full refactor of the GRC721 package and we won't have issues with this :)

I completely agree that the current GRC721 implementation could benefit from a full refactor. I’ve already started considering some approaches to address these issues. However, the current implementation of grc721_metadata.gno is completely unusable, so I believe merging this PR is a necessary step to make it functional until a more comprehensive refactor can be completed.

[r3v4s]

I really don't have strong opinion for this pr, because full refactoring grc721 won't produce this kind of issues anymore.

For short-term solution, looks good to me.