ServiceManager APIs for Remote Key Provisioning mainline module.

ServiceManager.getDeclaredInstances is needed for Remote Key
Provisioning mainline module to get all the implementations for
IRemotelyProvisionedComponent.

Test: build + usage in Remote Key Provisioning mainline module.
Change-Id: I92545104fa9bc190fe7c2f84b33d5f8693fcc2a4

core/api/module-lib-current.txt

@@ -348,6 +348,7 @@ package android.os {
   }
 
   public final class ServiceManager {
+    method @NonNull public static String[] getDeclaredInstances(@NonNull String);
     method public static boolean isDeclared(@NonNull String);
     method @Nullable public static android.os.IBinder waitForDeclaredService(@NonNull String);
   }

core/java/android/os/ServiceManager.java

@@ -258,12 +258,14 @@ public final class ServiceManager {
      * waitForService should always be able to return the service.
      * @hide
      */
+    @SystemApi(client = SystemApi.Client.MODULE_LIBRARIES)
+    @NonNull
     public static String[] getDeclaredInstances(@NonNull String iface) {
         try {
             return getIServiceManager().getDeclaredInstances(iface);
         } catch (RemoteException e) {
             Log.e(TAG, "error in getDeclaredInstances", e);
-            return null;
+            throw e.rethrowFromSystemServer();
         }
     }