Mint NFT via create thing mutation

![Image](https://user-images.githubusercontent.com/16282460/184685190-16598f4f-3904-4d33-a5cc-ac18db8ef896.png)

Relevant resources:

[NEAR Blockchain onboarding](https://docs.near.org/concepts/web3/nfts#blockchain-onboarding)
[Guest account from web client](https://github.com/deprecated-near-apps/nft-launcher)
[Sub account from server](https://github.com/near-examples/near-api-rest-server)
 