✨ Add option to change disable default nfts loading

[GabrielePicco]

Add option to change disable default nfts loading

Status	Type	⚠️ Core Change	Issue
Ready	Feature	No	-

Problem

Nfts are loaded by default when registering, this may not always be desired.

Solution

Added to boolean to change the default configuration.

1. Web.LoadNftsTextureByDefault change the loading mechanism to only retrieve NFT metadata.

    private void OnEnable()
    {
        Web3.LoadNftsTextureByDefault = false;
        Web3.OnNFTsUpdate += OnNFTsUpdate;
    }
    
    private void OnDisable()
    {
        Web3.OnNFTsUpdate -= OnNFTsUpdate;
    }

    private void OnNFTsUpdate(List<Nft> nfts, int total)
    {
       // Nfts won't have the textures
    }

2. Web.AutoLoadNfts controls the auto loading after the login, if set to false it can still be triggered manually calling LoadNFTs:

await Web3.LoadNFTs(loadTexture: false);