Fetch NFT metadata with storage iteration

[nvdtf]

With the release of storage iteration, it should be possible to enumerate all NFTs an account owns and return the metadata without explicitly importing the specific NFT contract. Currently, this use case is handled by the NFT Catalog.

We need to add sample scripts that use storage iteration to return NFT information about assets an account owns.

[joshuahannan]

Flow View has scripts that do part of this in their repo: https://github.com/33-Labs/flowview/blob/main/flow/scripts.js

It would be nice if we could have those as examples here too with more metadata stuff included.

Any help would be appreciated from any open source contributors! This would just require copying some of the scripts over and writing some tests for them.