Make aconfig flags generate a library instead of a srcjar.

Also add unit tests for the rest of device_config

Bug: 283475679
Test: m nothing (soong unit tests)
Change-Id: Iee18a1f2f2cbb23e8c8d84c54e903b32be29a693
diff --git a/java/Android.bp b/java/Android.bp
index 4af2a14..e079869 100644
--- a/java/Android.bp
+++ b/java/Android.bp
@@ -48,6 +48,7 @@
         "droidstubs.go",
         "fuzz.go",
         "gen.go",
+        "generated_java_library.go",
         "genrule.go",
         "hiddenapi.go",
         "hiddenapi_modular.go",
@@ -92,6 +93,7 @@
         "droidstubs_test.go",
         "fuzz_test.go",
         "genrule_test.go",
+        "generated_java_library_test.go",
         "hiddenapi_singleton_test.go",
         "jacoco_test.go",
         "java_test.go",