add veilid flutter plugin skeleton

veilid-flutter/ios/Classes/SwiftVeilidPlugin.swift

@@ -0,0 +1,14 @@
+import Flutter
+import UIKit
+
+public class SwiftVeilidPlugin: NSObject, FlutterPlugin {
+  public static func register(with registrar: FlutterPluginRegistrar) {
+    let channel = FlutterMethodChannel(name: "veilid", binaryMessenger: registrar.messenger())
+    let instance = SwiftVeilidPlugin()
+    registrar.addMethodCallDelegate(instance, channel: channel)
+  }
+
+  public func handle(_ call: FlutterMethodCall, result: @escaping FlutterResult) {
+    result("iOS " + UIDevice.current.systemVersion)
+  }
+}