[AGP 9] Migrate plugins to support AGP 9

[jesswrd]

Continuation of this PR: #11798

Migrates the rest of the plugins (and their respective example apps) that apply KGP to Built-in kotlin. Added validation for the plugin's build.gradle(.kts)

Will migrate all example apps to built-in kotlin and add validation for example apps here.

Fixes flutter/flutter#187261

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• I linked to at least one issue that this PR fixes in the description above.
• I followed the version and CHANGELOG instructions, using semantic versioning and the repository CHANGELOG style, or I have commented below to indicate which documented exception this PR falls under¹.
• I updated/added any relevant documentation (doc comments with ///).
• I added new tests to check the change I am making, or I have commented below to indicate which test exemption this PR falls under¹.
• All existing and new tests are passing.

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Footnotes

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[gemini-code-assist]

Code Review

This pull request migrates multiple Android plugin packages and their example apps to built-in Kotlin to support AGP 9, updates the minimum supported SDK version to Flutter 3.44/Dart 3.12, and updates the repository's Gradle validator tool to enforce these new conventions. Feedback on the changes includes: updating the automatically added android.builtInKotlin and android.newDsl flags to true in gradle.properties to prevent compilation failures; fixing a potential crash in the Gradle validator when javaVersions is empty, as well as correcting its nested block detection logic; and removing redundant try-catch blocks in the integration tests for file_selector_android and quick_actions_android where SDK version checks already handle the restricted broadcast.

[gemini-code-assist]

Since this PR explicitly migrates the plugins and their example apps to use the new Gradle plugins DSL and built-in Kotlin (by removing id("kotlin-android") and updating the Gradle/Kotlin versions), these flags should be set to true.

If android.builtInKotlin is left as false, the Flutter Gradle plugin will not automatically apply Kotlin, and since kotlin-android was removed, Kotlin compilation will fail. Similarly, android.newDsl should be true since the project has been migrated to the new declarative plugins DSL in settings.gradle.kts.

Note: Please apply this change to all other gradle.properties files modified in this PR.

# This builtInKotlin flag was added automatically by Flutter migrator
android.builtInKotlin=true
# This newDsl flag was added automatically by Flutter migrator
android.newDsl=true

[gemini-code-assist]

Using gradleLines.indexWhere only finds the first occurrence of compilerOptions. If a build.gradle.kts file has a valid compilerOptions block at the top-level, but also has an invalid nested compilerOptions block inside the android block, compilerOptionsIndex will point to the first (valid) one, and this validator will fail to detect the invalid nested block.

Instead of using indexWhere, we can directly check if any line within the android block boundaries contains compilerOptions.

    for (int i = androidIndex + 1; i < androidEndIndex; i++) {
      final String line = gradleLines[i];
      if (line.contains('compilerOptions') && !_isCommented(line)) {
        return true;
      }
    }
    return false;

[gemini-code-assist]

Since Build.VERSION.SDK_INT >= Build.VERSION_CODES.S is checked and returns early at the beginning of the method, the try-catch block catching SecurityException is redundant. The restriction on ACTION_CLOSE_SYSTEM_DIALOGS and the resulting SecurityException are only present on Android 12 (S) and above.

                Intent closeDialog = new Intent(Intent.ACTION_CLOSE_SYSTEM_DIALOGS);
                activity.sendBroadcast(closeDialog);

[gemini-code-assist]

Since Build.VERSION.SDK_INT >= Build.VERSION_CODES.S is checked and returns early at the beginning of the method, the try-catch block catching SecurityException is redundant. The restriction on ACTION_CLOSE_SYSTEM_DIALOGS and the resulting SecurityException are only present on Android 12 (S) and above.

    context.sendBroadcast(new Intent(Intent.ACTION_CLOSE_SYSTEM_DIALOGS));

[gemini-code-assist]

If a build.gradle.kts file does not specify any JavaVersion or JvmTarget (for example, a pure Java plugin or one with default compatibility settings), javaVersions will be empty. Calling javaVersions.first on an empty list will throw a StateError and crash the validator tool. Adding a guard check prevents this crash.

    if (javaVersions.isEmpty) {
      return true;
    }
    final int version = int.parse(javaVersions.first);