Added BlindBOX feature

[Shiba-Matic]

Added BlindBOX feature

This is my suggestion, when the user MINT blind box, can add a parameter, the user can choose to reveal the blind box immediately, and show the NFT data, or can wait for the public reveal. I think that's a good idea. Hope you can update.

bool public blindBoxOpen;
bool public useBlind;

function setBlindBoxOpened() public onlyOwner {
    blindBoxOpen = !blindBoxOpen;
}

function setUseBlind() public onlyOwner {
    useBlind = !useBlind;
}

function tokenURI(uint256 tokenId) public view virtual override returns (string memory) {
require(_exists(tokenId), 'ERC721Metadata: URI query for nonexistent token');

    if(useBlind) {
        if (blindBoxOpen) {
            string memory baseURI = _baseURI();
            return bytes(baseURI).length != 0 ? string(abi.encodePacked(baseURI, tokenId.toString())) : '';
        } else {
            return blindTokenURI;
![fea342d07e0634c8f0eaae5a19278a03](https://user-images.githubusercontent.com/93400912/162005345-92d3743f-c593-48dd-81d6-e73fac343a59.jpg)

        }
    } else {
        string memory baseURI = _baseURI();
        return bytes(baseURI).length != 0 ? string(abi.encodePacked(baseURI, tokenId.toString())) : '';    
    }
}