refactor cocoapods validator to detect broken install (#38560)

packages/flutter_tools/lib/src/base/user_messages.dart

diff --git a/packages/flutter_tools/lib/src/base/user_messages.dart b/packages/flutter_tools/lib/src/base/user_messages.dart
index 1764483..a1f1d91 100644
--- a/packages/flutter_tools/lib/src/base/user_messages.dart
+++ b/packages/flutter_tools/lib/src/base/user_messages.dart
@@ -172,6 +172,11 @@
       '$consequence\n'
       'To upgrade:\n'
       '$upgradeInstructions';
+  String cocoaPodsBrokenInstall(String consequence, String reinstallInstructions) =>
+      'CocoaPods installed but not working.\n'
+      '$consequence\n'
+      'To re-install CocoaPods, run:\n'
+      '$reinstallInstructions';
 
   // Messages used in VsCodeValidator
   String vsCodeVersion(String version) => 'version $version';