Add test for engine artifact framework permissions (#148786)

Framework test to validate the iOS and macOS framework engine artifacts (Flutter.framework and FlutterMacOS.framework) have read and executable permissions.

~~Will fail until flutter/engine#52961 rolls.~~ <-- it rolled flutter/flutter#148819

Author: jmagman

packages/flutter_tools/test/host_cross_arch.shard/ios_content_validation_test.dart

@@ -463,10 +463,9 @@ void main() {
       );
       expect(appCodesign, const ProcessResultMatcher());
 
-      // Check read/write permissions are being correctly set
-      final String rawStatString = flutterFrameworkDir.statSync().modeString();
-      final String statString = rawStatString.substring(rawStatString.length - 9);
-      expect(statString, 'rwxr-xr-x');
+      // Check read/write permissions are being correctly set.
+      final String statString = flutterFrameworkDir.statSync().mode.toRadixString(8);
+      expect(statString, '40755');
     });
   }, skip: !platform.isMacOS, // [intended] only makes sense for macos platform.
      timeout: const Timeout(Duration(minutes: 10))

packages/flutter_tools/test/host_cross_arch.shard/macos_content_validation_test.dart

@@ -41,7 +41,7 @@ void main() {
 
     final Directory tempDir = createResolvedTempDirectorySync('macos_content_validation.');
 
-    // Pre-cache iOS engine Flutter.xcframework artifacts.
+    // Pre-cache macOS engine FlutterMacOS.xcframework artifacts.
     final ProcessResult result = processManager.runSync(
       <String>[
         flutterBin,
@@ -54,6 +54,17 @@ void main() {
 
     expect(result, const ProcessResultMatcher());
     expect(xcframeworkArtifact.existsSync(), isTrue);
+
+    final Directory frameworkArtifact = fileSystem.directory(
+      fileSystem.path.joinAll(<String>[
+        xcframeworkArtifact.path,
+        'macos-arm64_x86_64',
+        'FlutterMacOS.framework',
+      ]),
+    );
+    // Check read/write permissions are set correctly in the framework engine artifact.
+    final String artifactStat = frameworkArtifact.statSync().mode.toRadixString(8);
+    expect(artifactStat, '40755');
   });
 
   for (final String buildMode in <String>['Debug', 'Release']) {
@@ -164,10 +175,9 @@ void main() {
         ),
       );
 
-      // Check read/write permissions are being correctly set
-      final String rawStatString = outputFlutterFramework.statSync().modeString();
-      final String statString = rawStatString.substring(rawStatString.length - 9);
-      expect(statString, 'rwxr-xr-x');
+      // Check read/write permissions are being correctly set.
+      final String outputFrameworkStat = outputFlutterFramework.statSync().mode.toRadixString(8);
+      expect(outputFrameworkStat, '40755');
 
       // Check complicated macOS framework symlink structure.
       final Link current = outputFlutterFramework.childDirectory('Versions').childLink('Current');