Simplify the delegates

[fpseverino]

• Make PersonalizationJSON a struct instead of a protocol.
  • It was missing only a field that we can make optional, now users directly create the struct and we handle the JSON encoding
• Move all the signing information from the delegates to the actual services' classes
  • Now users aren't required to use specific URL's initializers, they just pass the path as a String and we create the URL
  • The goal is to completely remove the delegates in the future and move the remaining functions to the PassDataModel and OrderDataModel protocols
• Make the template delegate method return a String instead of a URL
  • The user provides the path to the directory and we initialize the URL

[MahdiBM]

Looks good to me as long as the tests pass.