User Discovery Environment

• Add UDEnvironment struct that wraps ud address, cert, and contact into a single model.
• Use UDEnvironment in XXMessengerClient

Sources/XXClient/Functions/NewOrLoadUd.swift

@@ -3,6 +3,20 @@ import XCTestDynamicOverlay
 
 public struct NewOrLoadUd {
   public struct Params: Equatable {
+    public init(
+      e2eId: Int,
+      username: String?,
+      registrationValidationSignature: Data?,
+      environment: UDEnvironment
+    ) {
+      self.e2eId = e2eId
+      self.username = username
+      self.registrationValidationSignature = registrationValidationSignature
+      self.cert = environment.cert
+      self.contact = environment.contact
+      self.address = environment.address
+    }
+
     public init(
       e2eId: Int,
       username: String?,