Implement the NonFungibleToken and INFT interfaces

[D10100111001]

Is your feature request related to a problem? Please describe.
The cryptodappy DappyContract smart contract does not implement the NonFungibleToken contract interface and the Dappy resource does not implement the INFT interface.

It would be good for it to be consistent with how NFTs should be created practically.

Describe the solution you'd like
Create a new optional, advanced mission that walks user through the step of implementing the interfaces.

Another option is to give users hints and notes that the DappyContract smart contract requires implementation of the aforementioned interfaces in practical applications.

Either way, there should be a DappyNFTContract.cdc file in the final mission's code that shows how the smart contract with the interfaces implemented should look so users who are keen to learn more have a reference point.

Additional context
Since cryptodappy was created for learning purposes, it is understandable why it doesn't comply with the interfaces but it would still be a good idea to let users understand the implementation of the interfaces.

[bebner]

Hey @D10100111001, thanks for bringing this up. You're right, because of its educational nature and appeal to a beginner audience, CryptoDappy takes some shortcuts. However, this issue was surfaced internally too, and we will work on this as soon as possible to let the DappyNFTContract implement the NFT interface - as it should. Will keep you updated here.