Customize the decoder with a keyDecodingStrategy

[kevinrenskers]

I'd like to be able to set the keyDecodingStrategy of the default JSONDecoder to .convertFromSnakeCase, but that doesn't seem possible at the moment?

So instead I now have to give the CodingKeys by hand.

struct Upload: Codable {
  let id: Int
  let user: User
  let mediaType: String
  let image: String
  let thumbnail: String
  let description: String

  enum CodingKeys: String, CodingKey {
    case id
    case user
    case mediaType = "media_type"
    case image
    case thumbnail
    case description
  }
}

This is a little bit annoying considering all of that could be automated away with setting the keyDecodingStrategy :)

This could be done the same way that the date encoding strategy can already be customized.