Generate an api-versions.xml from stubs jar

The current api-versions.xml shipped in the SDK and used internally in
the android build system is generated by the framework-doc-stubs target.

This CL adds a new target that generates an (almost) equivalent database
in a different way. There are a few upshots of using this method to
generate them:
- using the framework-doc-stubs target is inefficient. It runs late in
  the build but also takes a long time, extending the critical path of
  the modules that depend on api-versions.xml
- the framework-doc-system-stubs target is using module sources as
  input, which is desireable to avoid because we want to separate
  module sources from the rest of the platform.

Bug: 187398174
Bug: 186197911
Test: m api_versions_{public,system} && diff with "originals"
Change-Id: I8adab94ee7ca0bee4fc0be8d99f1125360387d89

StubLibraries.bp

@@ -365,6 +365,64 @@ java_library {
     },
 }
 
+////////////////////////////////////////////////////////////////////////
+// api-versions.xml generation, for public and system. This API database
+// also contains the android.test.* APIs.
+////////////////////////////////////////////////////////////////////////
+
+java_library {
+    name: "android_stubs_current_with_test_libs",
+    static_libs: [
+        "android_stubs_current",
+        "android.test.base.stubs",
+        "android.test.mock.stubs",
+        "android.test.runner.stubs",
+    ],
+    defaults: ["android.jar_defaults"],
+    visibility: [
+        "//visibility:override",
+        "//visibility:private",
+    ],
+}
+
+java_library {
+    name: "android_system_stubs_current_with_test_libs",
+    static_libs: [
+        "android_system_stubs_current",
+        "android.test.base.stubs.system",
+        "android.test.mock.stubs.system",
+        "android.test.runner.stubs.system",
+    ],
+    defaults: ["android.jar_defaults"],
+    visibility: [
+        "//visibility:override",
+        "//visibility:private",
+    ],
+}
+
+droidstubs {
+    name: "api_versions_public",
+    srcs: [":android_stubs_current_with_test_libs{.jar}"],
+    generate_stubs: false,
+    api_levels_annotations_enabled: true,
+    api_levels_annotations_dirs: [
+        "sdk-dir",
+        "api-versions-jars-dir",
+    ],
+}
+
+droidstubs {
+    name: "api_versions_system",
+    srcs: [":android_system_stubs_current_with_test_libs{.jar}"],
+    generate_stubs: false,
+    api_levels_annotations_enabled: true,
+    api_levels_annotations_dirs: [
+        "sdk-dir",
+        "api-versions-jars-dir",
+    ],
+    api_levels_sdk_type: "system",
+}
+
 /////////////////////////////////////////////////////////////////////
 // hwbinder.stubs provides APIs required for building HIDL Java
 // libraries.