closes #issue136763, changed a command to generate gradle error message according to platform (flutter#149877)

Currently, the error message displayed to regenerate the lockfiles gives a Unix-like command ./gradlew, which will be incorrect for Windows environments. This PR uses globals.platform.isWindows to give the appropriate command.

closes flutter#136763

Author: D-extremity

packages/flutter_tools/lib/src/android/gradle_errors.dart

@@ -414,8 +414,9 @@ final GradleHandledError lockFileDepMissingHandler = GradleHandledError(
     final File gradleFile = project.directory
         .childDirectory('android')
         .childFile('build.gradle');
+        final String generatedGradleCommand = globals.platform.isWindows ? r'.\gradlew.bat' : './gradlew';
     final String textInBold = globals.logger.terminal.bolden(
-      'To regenerate the lockfiles run: `./gradlew :generateLockfiles` in ${gradleFile.path}\n'
+      'To regenerate the lockfiles run: `$generatedGradleCommand :generateLockfiles` in ${gradleFile.path}\n'
       'To remove dependency locking, remove the `dependencyLocking` from ${gradleFile.path}'
     );
     globals.printBox(

packages/flutter_tools/test/general.shard/android/gradle_errors_test.dart

@@ -782,8 +782,7 @@ Execution failed for task ':app:generateDebugFeatureTransitiveDeps'.
           '│ To regenerate the lockfiles run: `./gradlew :generateLockfiles` in /android/build.gradle │\n'
           '│ To remove dependency locking, remove the `dependencyLocking` from /android/build.gradle  │\n'
           '└──────────────────────────────────────────────────────────────────────────────────────────┘\n'
-        )
-      );
+        ));
     }, overrides: <Type, Generator>{
       GradleUtils: () => FakeGradleUtils(),
       Platform: () => fakePlatform('android'),
@@ -792,6 +791,54 @@ Execution failed for task ':app:generateDebugFeatureTransitiveDeps'.
     });
   });
 
+  testUsingContext('generates correct gradle command for Unix-like environment',
+      () async {
+    await lockFileDepMissingHandler.handler(
+      project: FlutterProject.fromDirectoryTest(fileSystem.currentDirectory),
+      usesAndroidX: true,
+      line: '',
+    );
+
+    expect(
+        testLogger.statusText,
+        contains('\n'
+            '┌─ Flutter Fix ────────────────────────────────────────────────────────────────────────────┐\n'
+            '│ You need to update the lockfile, or disable Gradle dependency locking.                   │\n'
+            '│ To regenerate the lockfiles run: `./gradlew :generateLockfiles` in /android/build.gradle │\n'
+            '│ To remove dependency locking, remove the `dependencyLocking` from /android/build.gradle  │\n'
+            '└──────────────────────────────────────────────────────────────────────────────────────────┘\n'
+            ''));
+  }, overrides: <Type, Generator>{
+    GradleUtils: () => FakeGradleUtils(),
+    Platform: () => fakePlatform('linux'),
+    FileSystem: () => fileSystem,
+    ProcessManager: () => processManager,
+  });
+
+
+    testUsingContext('generates correct gradle command for windows environment',
+      () async {
+    await lockFileDepMissingHandler.handler(
+      project: FlutterProject.fromDirectoryTest(fileSystem.currentDirectory),
+      usesAndroidX: true,
+      line: '',
+    );
+    expect(
+        testLogger.statusText,
+        contains('\n'
+            '┌─ Flutter Fix ────────────────────────────────────────────────────────────────────────────────┐\n'
+            '│ You need to update the lockfile, or disable Gradle dependency locking.                       │\n'
+            '│ To regenerate the lockfiles run: `.\\gradlew.bat :generateLockfiles` in /android/build.gradle │\n'
+            '│ To remove dependency locking, remove the `dependencyLocking` from /android/build.gradle      │\n'
+            '└──────────────────────────────────────────────────────────────────────────────────────────────┘\n'
+            ''));
+  }, overrides: <Type, Generator>{
+    GradleUtils: () => FakeGradleUtils(),
+    Platform: () => fakePlatform('windows'),
+    FileSystem: () => fileSystem,
+    ProcessManager: () => processManager,
+  });
+
   group('Incompatible Kotlin version', () {
     testWithoutContext('pattern', () {
       expect(