Restore contacts from backup

XXClient library

• Improve error handling in UdMultiLookupCallback.

xx-messenger example

• Improve backup restoration.
• Restore contacts.
• Add contact lookup feature.
• Display contact ids.
• Improve sending requests.
• Restore username from restored facts, not from restored params.

Examples/xx-messenger/Sources/MyContactFeature/MyContactView.swift

+import AppCore
 import ComposableArchitecture
 import SwiftUI
 import XXModels
@@ -49,8 +50,17 @@ public struct MyContactView: View {
   public var body: some View {
     WithViewStore(store, observe: ViewState.init) { viewStore in
       Form {
+        Section {
+          Text(viewStore.contact?.id.hexString ?? "")
+            .font(.footnote.monospaced())
+            .textSelection(.enabled)
+        } header: {
+          Label("ID", systemImage: "number")
+        }
+
         Section {
           Text(viewStore.contact?.username ?? "")
+            .textSelection(.enabled)
         } header: {
           Label("Username", systemImage: "person")
         }
@@ -59,6 +69,7 @@ public struct MyContactView: View {
           if let contact = viewStore.contact {
             if let email = contact.email {
               Text(email)
+                .textSelection(.enabled)
               Button(role: .destructive) {
                 viewStore.send(.unregisterEmailTapped)
               } label: {
@@ -135,6 +146,7 @@ public struct MyContactView: View {
           if let contact = viewStore.contact {
             if let phone = contact.phone {
               Text(phone)
+                .textSelection(.enabled)
               Button(role: .destructive) {
                 viewStore.send(.unregisterPhoneTapped)
               } label: {