Sort Swift imports in templates (#141487)

`swift-format` alphabetizes imports.  Alphabetize them in swift template files and integration tests.

I found this as part of https://github.com/flutter/flutter/issues/41129 running `swift-import` on packages.

dev/a11y_assessments/ios/Runner/AppDelegate.swift

@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import UIKit
 import Flutter
+import UIKit
 
 @UIApplicationMain
 @objc class AppDelegate: FlutterAppDelegate {

dev/a11y_assessments/macos/RunnerTests/RunnerTests.swift

@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import FlutterMacOS
 import Cocoa
+import FlutterMacOS
 import XCTest
 
 class RunnerTests: XCTestCase {

dev/benchmarks/complex_layout/ios/Runner/AppDelegate.swift

@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import UIKit
 import Flutter
+import UIKit
 
 @UIApplicationMain
 @objc class AppDelegate: FlutterAppDelegate {

dev/integration_tests/ios_app_with_extensions/ios/Runner/AppDelegate.swift

@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import UIKit
 import Flutter
+import UIKit
 
 @UIApplicationMain
 @objc class AppDelegate: FlutterAppDelegate {

dev/integration_tests/ios_app_with_extensions/ios/watch Extension/HostingController.swift

@@ -9,9 +9,9 @@
 //  Created by Georg Wechslberger on 08.04.20.
 //
 
-import WatchKit
 import Foundation
 import SwiftUI
+import WatchKit
 
 class HostingController: WKHostingController<ContentView> {
     override var body: ContentView {

dev/integration_tests/non_nullable/ios/Runner/AppDelegate.swift

@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import UIKit
 import Flutter
+import UIKit
 
 @UIApplicationMain
 @objc class AppDelegate: FlutterAppDelegate {

dev/manual_tests/ios/Runner/AppDelegate.swift

@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import UIKit
 import Flutter
+import UIKit
 
 @UIApplicationMain
 @objc class AppDelegate: FlutterAppDelegate {

packages/flutter_tools/templates/app_shared/ios-swift.tmpl/Runner/AppDelegate.swift

-import UIKit
 import Flutter
+import UIKit
 
 @UIApplicationMain
 @objc class AppDelegate: FlutterAppDelegate {

packages/flutter_tools/templates/app_shared/macos.tmpl/RunnerTests/RunnerTests.swift.tmpl

-import FlutterMacOS
 import Cocoa
+import FlutterMacOS
 import XCTest
 {{#withPlatformChannelPluginHook}}