Add ERC: NFT Metadata Extension like JSON-LD

[yoheinishikubo]

When opening a pull request to submit a new EIP, please use the suggested template: https://github.com/ethereum/EIPs/blob/master/eip-template.md

We have a GitHub bot that automatically merges some PRs. It will merge yours immediately if certain criteria are met:

• The PR edits only existing draft PRs.
• The build passes.
• Your GitHub username or email address is listed in the 'author' header of all affected PRs, inside .
• If matching on email address, the email address is the one publicly listed on your GitHub profile.

[eip-review-bot]

✅ All reviewers have approved.

[SamWilsn]

What is this exactly?

[yoheinishikubo]

@SamWilsn Apologies for the delay.

I've been involved with projects that use NFTs as proof of event attendance and for carbon offsetting flights. These initiatives follow existing standards, some of which are documented on Schema.org.

While there are numerous similar projects, they often employ varying data schemas, making it nearly impossible to integrate all the data seamlessly.

To address this, I propose adopting universal standards for NFT metadata that computers can easily utilize, akin to how HTML serves humans and JSON-LD serves computers.

[github-actions[bot]]

The commit 4df3c66351573de7bf38ca596166904bb9ed7380 (as a parent of 257abc41e057a7f1976420a1bf629df9a63ce478) contains errors. Please inspect the Run Summary for details.

[yoheinishikubo]

@SamWilsn Apologies for the confusion. It seems I made an error while migrating this PR from the original repository, resulting in it being empty. Could you please review the current status again?