Support NFT asset for CCTX and have a standard like ZRC20

[lumtis]

Is your feature request related to a problem? Please describe.

Extending ability to interact with ZetaChain with new class of asset like NFTs

Describe the solution you'd like

The most basic standard for NFT is ERC721.

We could represent the standard ZRC721.

In connected chain

A NFTCustody/ERC721Custody contract is created as an asset handler to lock asset deposited on ZetaChain. Should have lot of similarities with ERC20.

When doing arbitrary smart contract calls, the asset would be handled like ERC20: using the approval system to allow the target contract to use the asset.

On Protocol

Changes in fungible module necessary to represent the asset.
New workflow path in crosschain to determine how asset is handled.

Follow-up

The functionality can be extended similar to ERC20 with the ability to withdraw on any chains:

#2740
#2741