Add support for .aar files (Android .jar files)

Ale doesn't recognize imports from .aar files (Android .jar files). Encountered this while working on Godot Android plugins.
To reproduce, clone e.g. [Godot Google Play Billing](https://github.com/godotengine/godot-google-play-billing). Download the required aar file from [this page](https://godotengine.org/download/linux/) and place it in `godot-google-play-billing/godot-google-play-billing/libs/` and edit GodotGooglePlayBilling.java observing that the `import org.godotengine.godot.*` and `import com.android.billingclient.api.*` lines are errors but the other imports work. And note that with the .aar file installed (as above) the `./.gradlew build` command does work, so the project is set up correctly.