copy JNI from AAR files to android_app APK

JNI libs present in AAR files are ignored in the build. If those
libraries are necessary, they must be manually extracted and a
prebuilt_cc_library module must be created for them. Instead, we can
extract these libraries and copy them to an output APK as part of the build.

Bug: 228848794
Test: created android_app that depends on an android_library_import with
  JNI embedded, and verified that .so libs are present in APK
Test: created android_app that depends on an android_library which
  depends on android_library_import with JNI embedded, and verified
  that .so libs are present in APK
Test: verified that multiple .so's from a single architecture are copied
  to APK
Test: verified that the absence of a jni/<arch> folder or files in the
  folder will cause the Ninja action to error
Change-Id: I242a862d7bd881f7a4a8c23493924d8fe441ea25
diff --git a/java/app_import.go b/java/app_import.go
index b017eca..9d199d6 100644
--- a/java/app_import.go
+++ b/java/app_import.go
@@ -256,7 +256,7 @@
 		ctx.ModuleErrorf("One and only one of certficate, presigned, and default_dev_cert properties must be set")
 	}
 
-	_, certificates := collectAppDeps(ctx, a, false, false)
+	_, _, certificates := collectAppDeps(ctx, a, false, false)
 
 	// TODO: LOCAL_EXTRACT_APK/LOCAL_EXTRACT_DPI_APK
 	// TODO: LOCAL_PACKAGE_SPLITS