Add the implementation of get all packages in

IPackageManagerNative.aidl.

The implementation is mostly a copy from getAllPackages of
IPackageManager.

Bug: 137785555
Test: A toy program to print all packages
Change-Id: I9eb9ea94c7b35557156f08ec22c1f26793bb862a

services/core/java/com/android/server/pm/PackageManagerService.java

@@ -22652,6 +22652,11 @@ public class PackageManagerService extends IPackageManager.Stub
     }
 
     private class PackageManagerNative extends IPackageManagerNative.Stub {
+        @Override
+        public String[] getAllPackages() {
+            return PackageManagerService.this.getAllPackages().toArray(new String[0]);
+        }
+
         @Override
         public String[] getNamesForUids(int[] uids) throws RemoteException {
             final String[] results = PackageManagerService.this.getNamesForUids(uids);