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/ContactFromIdentityProvider.swift

 import Bindings
 
 public struct ContactFromIdentityProvider {
-  public var get: (Data) throws -> Data
+  public var get: (Identity) throws -> Data
 
-  public func callAsFunction(identity: Data) throws -> Data {
+  public func callAsFunction(identity: Identity) throws -> Data {
     try get(identity)
   }
 }
 
 extension ContactFromIdentityProvider {
   public static func live(bindingsClient: BindingsClient) -> ContactFromIdentityProvider {
-    ContactFromIdentityProvider(get: bindingsClient.getContactFromIdentity(_:))
+    ContactFromIdentityProvider { identity in
+      let encoder = JSONEncoder()
+      let identityData = try encoder.encode(identity)
+      let contactData = try bindingsClient.getContactFromIdentity(identityData)
+      return contactData
+    }
   }
 }