Increase Xcode minimum version to 14 (#125639)

Looks like CocoaPods 1.12.1 is incompatible with < Xcode 14 due to https://github.com/CocoaPods/CocoaPods/pull/11828 (see https://github.com/flutter/flutter/issues/123890 for context).

Bump the minimum Xcode version allowed by tooling to 14, released September 2022.

```
[!] Xcode - develop for iOS and macOS (Xcode 13.4)
    ✗ Flutter requires Xcode 14 or higher.
      Download the latest version or update via the Mac App Store.
```

Fixes https://github.com/flutter/flutter/issues/125286.
Previous bump at #97746.

packages/flutter_tools/lib/src/macos/xcode.dart

@@ -18,7 +18,7 @@ import '../base/version.dart';
 import '../build_info.dart';
 import '../ios/xcodeproj.dart';
 
-Version get xcodeRequiredVersion => Version(13, null, null);
+Version get xcodeRequiredVersion => Version(14, null, null);
 
 /// Diverging this number from the minimum required version will provide a doctor
 /// warning, not error, that users should upgrade Xcode.

packages/flutter_tools/test/general.shard/macos/xcode_test.dart

@@ -155,7 +155,7 @@ void main() {
 
         testWithoutContext('version checks pass when version meets minimum', () {
           xcodeProjectInterpreter.isInstalled = true;
-          xcodeProjectInterpreter.version = Version(13, null, null);
+          xcodeProjectInterpreter.version = Version(14, null, null);
 
           expect(xcode.isRequiredVersionSatisfactory, isTrue);
           expect(xcode.isRecommendedVersionSatisfactory, isTrue);
@@ -163,7 +163,7 @@ void main() {
 
         testWithoutContext('version checks pass when major version exceeds minimum', () {
           xcodeProjectInterpreter.isInstalled = true;
-          xcodeProjectInterpreter.version = Version(14, 0, 0);
+          xcodeProjectInterpreter.version = Version(15, 0, 0);
 
           expect(xcode.isRequiredVersionSatisfactory, isTrue);
           expect(xcode.isRecommendedVersionSatisfactory, isTrue);
@@ -171,7 +171,7 @@ void main() {
 
         testWithoutContext('version checks pass when minor version exceeds minimum', () {
           xcodeProjectInterpreter.isInstalled = true;
-          xcodeProjectInterpreter.version = Version(13, 3, 0);
+          xcodeProjectInterpreter.version = Version(14, 3, 0);
 
           expect(xcode.isRequiredVersionSatisfactory, isTrue);
           expect(xcode.isRecommendedVersionSatisfactory, isTrue);
@@ -179,7 +179,7 @@ void main() {
 
         testWithoutContext('version checks pass when patch version exceeds minimum', () {
           xcodeProjectInterpreter.isInstalled = true;
-          xcodeProjectInterpreter.version = Version(13, 0, 2);
+          xcodeProjectInterpreter.version = Version(14, 0, 2);
 
           expect(xcode.isRequiredVersionSatisfactory, isTrue);
           expect(xcode.isRecommendedVersionSatisfactory, isTrue);
@@ -202,7 +202,7 @@ void main() {
 
         testWithoutContext('isInstalledAndMeetsVersionCheck is true when macOS and installed and version is satisfied', () {
           xcodeProjectInterpreter.isInstalled = true;
-          xcodeProjectInterpreter.version = Version(13, null, null);
+          xcodeProjectInterpreter.version = Version(14, null, null);
 
           expect(xcode.isInstalledAndMeetsVersionCheck, isTrue);
           expect(fakeProcessManager, hasNoRemainingExpectations);

packages/flutter_tools/test/general.shard/macos/xcode_validator_test.dart

@@ -56,7 +56,7 @@ void main() {
       final ValidationResult result = await validator.validate();
       expect(result.type, ValidationType.partial);
       expect(result.messages.last.type, ValidationMessageType.error);
-      expect(result.messages.last.message, contains('Flutter requires Xcode 13 or higher'));
+      expect(result.messages.last.message, contains('Flutter requires Xcode 14 or higher'));
     });
 
     testWithoutContext('Emits partial status when Xcode below recommended version', () async {

packages/flutter_tools/test/src/context.dart

@@ -326,13 +326,13 @@ class FakeXcodeProjectInterpreter implements XcodeProjectInterpreter {
   bool get isInstalled => true;
 
   @override
-  String get versionText => 'Xcode 13';
+  String get versionText => 'Xcode 14';
 
   @override
-  Version get version => Version(13, null, null);
+  Version get version => Version(14, null, null);
 
   @override
-  String get build => '13C100';
+  String get build => '14A309';
 
   @override
   Future<Map<String, String>> getBuildSettings(