Feature request: Add additional ways of (un)locking content.

[0xGeel]

Context

Currently, the only unlock criteria is owning NFTs. A Unlockable can be unlocked by the user holding NFTs with nftIds specified in the array. While this is a good start, there is value in unlocking content based on other criteria.

Here are ideas for other unlock criteria:

• Holding any of the nftIds specified in the array.
• Holding a NFT minted on a certain tokenAddress.
• Holding multiple NFTs minted on a certain tokenAddress.

Suggestions and ideas are very welcome! 🙏