Implement coreLibraryDesugaring feature

[jewelshkjony]

General items:

• I have updated the relevant documentation files under docs/
• My code follows the:
  • Google Java style guide (for .java files)
  • Google JavaScript style guide (for .js files)
• ant tests passes on my machine

For all other changes:

• I branched from master
• My pull request has master as the base

What does this PR accomplish?

This PR integrates coreLibraryDesugaring into the App Inventor build pipeline. It enables the use of modern Java 8+ APIs (such as java.time, java.util.stream, and default interface methods) while maintaining compatibility with older Android devices.

Key Changes:

• New Annotation: Added @UsesCoreLibraryDesugaring to allow components or extensions to signal when the desugaring process is required.
• Toolchain Updates:
  • Integrated latest desugar_jdk_libs-2.1.5.jar and its configuration JAR.
  • Updated D8.java to support the --desugared-lib flag.
  • Implemented L8.java to handle the dexing and shrinking of the desugar library itself.
• Build Pipeline: Modified the build logic to ensure the desugared library classes are correctly bundled into both APK and AAB outputs.

Performance Impact:

• APK Size: I observed an increase of approximately 1.01 MB± when desugaring is enabled.
• Build Time: It takes a few seconds extra to build the project when desugaring is enabled. (Extra 4 seconds in my test)

This change is particularly beneficial for extension developers, as it allows them to leverage modern Java features without worrying about manual backporting or breaking apps on older handsets.

Test Results:

Tested with a sample extension utilizing java.time and confirmed it runs perfectly.

Resolves # .
#3791

[AppInventorWorkerBee]

Can one of the admins verify this patch?

[AppInventorWorkerBee]

Can one of the admins verify this patch?

[jewelshkjony]

@AppInventorWorkerBee ok to test

[MahmoudHooda2019]

Great work @jewelshkjony
Waiting for this future 😊

[jisqyv]

@AppInventorWorkerBee ok to test