Add UdMultiLookupCallback

Sources/XXClient/Callbacks/UdMultiLookupCallback.swift

+import Bindings
+import XCTestDynamicOverlay
+
+public struct UdMultiLookupCallback {
+  public enum Result: Equatable {
+    case success([Contact])
+    case failure(error: NSError, failedIDs: [Data])
+  }
+
+  public init(handle: @escaping (Result) -> Void) {
+    self.handle = handle
+  }
+
+  public var handle: (Result) -> Void
+}
+
+extension UdMultiLookupCallback {
+  public static let unimplemented = UdMultiLookupCallback(
+    handle: XCTUnimplemented("\(Self.self)")
+  )
+}
+
+extension UdMultiLookupCallback {
+  func makeBindingsUdMultiLookupCallback() -> BindingsUdMultiLookupCallbackProtocol {
+    class CallbackObject: NSObject, BindingsUdMultiLookupCallbackProtocol {
+      init(_ callback: UdMultiLookupCallback) {
+        self.callback = callback
+      }
+
+      let callback: UdMultiLookupCallback
+
+      func callback(_ contactListJSON: Data?, failedIDs: Data?, err: Error?) {
+        if let err = err {
+          callback.handle(.failure(
+            error: err as NSError,
+            failedIDs: failedIDs
+              .map { (try? JSONDecoder().decode([Data].self, from: $0)) ?? [] } ?? []
+          ))
+        } else if let contactListJSON = contactListJSON {
+          do {
+            let contactsData = try JSONDecoder().decode([Data].self, from: contactListJSON)
+            let contacts: [Contact] = contactsData.map { Contact.live($0) }
+            callback.handle(.success(contacts))
+          } catch {
+            callback.handle(.failure(error: error as NSError, failedIDs: []))
+          }
+        } else {
+          fatalError("BindingsUdMultiLookupCallbackProtocol received `nil` contactListJSON and `nil` error")
+        }
+      }
+    }
+
+    return CallbackObject(self)
+  }
+}