Allow for extra image in metadata and to move image preview out of traits

[newbreedofgeek]

To fix:

#126

#125

[damienen]

Preview can be moved out of traits, but it's debatable if it should be moved as it allows people to quickly see the preview from the marketplace.

The bonus image trait is redundant as we should just use the MultiversX NFT standard

That would mean actively using the assets URIs. Those can be however many we want, more cam be updated to make the NFTs upgradable, etc.

[damienen]

Here's some documentation on it:
https://docs.multiversx.com/tokens/nft-tokens/#add-uris-to-nft

https://docs.multiversx.com/tokens/nft-tokens/#creation-of-an-nft see URIs at end of NFT creation

[newbreedofgeek]

that's fine, but we are going to aim to build this to be multi-chain compatible so we can bridge data nfts.

[UPDATE] But as per our discussions on the side, we will support BOTH adding to MvX NFT "Assets" and also on the NFT Metadata

[newbreedofgeek]

Looks good @damienen

Once confirmed to work via an alpha pubish on NPM and used by Data DEX, we can merge to develop.