Support CDN

[nikitosing]

in token instance structure will be new

• optional field thumbnails
  it has the following structure (example with full key set, it is possible that some keys will be absent due to small image size, or impossibility to upload original image):

thumbnails: 
{
  250x250: "https://pub-1f1ac54bb1ee4b1ab5f87ca95854800c.r2.dev/eth-sepolia-testnet/cef9dc82f65e2f8117a4edf5f4dc9d85d50d3f17_250x250.png",
  500x500: "https://pub-1f1ac54bb1ee4b1ab5f87ca95854800c.r2.dev/eth-sepolia-testnet/cef9dc82f65e2f8117a4edf5f4dc9d85d50d3f17_500x500.png",
  60x60: "https://pub-1f1ac54bb1ee4b1ab5f87ca95854800c.r2.dev/eth-sepolia-testnet/cef9dc82f65e2f8117a4edf5f4dc9d85d50d3f17_60x60.png",
  original: "https://pub-1f1ac54bb1ee4b1ab5f87ca95854800c.r2.dev/eth-sepolia-testnet/cef9dc82f65e2f8117a4edf5f4dc9d85d50d3f17_original.png"
}

• field media_url, it contains url to image OR animation (if image is miising)
  media_url: "https://d3onnejkzwg1si.cloudfront.net/640x640/wolvesnfts/3/Images/1784.png"
• optional field media_type it shows content type of media_url in the following format: "image/png"
media_type: "image/png"

Example:
https://eth-sepolia.k8s-dev.blockscout.com/api/v2/tokens/0x467f1c548E65bC5876b95b217dC6f0DDB801C83A/instances/2837

[nikitosing]

Backend PR: blockscout/blockscout#10675

[tom2drum]

As we discussed, we will ignore the media_type and media_url fields for now. In the future, we expect to have in API response separate media-type properties for both image_url and animation_url.

Additionally, we consider the new CDN and Helia verified fetch features to be mutually exclusive. For the CDN to work, Helia fetch should be disabled by setting NEXT_PUBLIC_HELIA_VERIFIED_FETCH_ENABLED=false.