Use codable models in API

This MR contains !9 (merged) and !11 (merged) (make sure to merge them before reviewing this MR)

• Update IdentityMaker to return Identity model.
• Update ConnectionMaker to accept Identity model.
• Use Message model in MessageListener.
• Use RestlikeMessage model in RestlikeRequestSender.
• Use MessageSendReport in MessageDeliveryWaiter.
• Use [Int] for rounds in MessageDeliveryWaiter.Result.delivered.
• Use Identity model in ContactFromIdentityProvider.
• Use Fact model in ContactFactsProvider.
• Use Fact model in ContactFactsSetter.

Sources/ElixxirDAppsSDK/IdentityMaker.swift

 import Bindings
 
 public struct IdentityMaker {
-  public var make: () throws -> Data
+  public var make: () throws -> Identity
 
-  public func callAsFunction() throws -> Data {
+  public func callAsFunction() throws -> Identity {
     try make()
   }
 }
@@ -11,7 +11,9 @@ public struct IdentityMaker {
 extension IdentityMaker {
   public static func live(bindingsClient: BindingsClient) -> IdentityMaker {
     IdentityMaker {
-      try bindingsClient.makeIdentity()
+      let data = try bindingsClient.makeIdentity()
+      let decoder = JSONDecoder()
+      return try decoder.decode(Identity.self, from: data)
     }
   }
 }