propagate retry policy on zipped (autobatched) queries

[googley42]

Currently withRetryPolicy only sets the policy on BatchGetItem/BatchWriteItem queries but not on autobatched queries.

We would like autobatched queries created with zip and forEach to honour withRetryPolicy method application.

One possible solution is to add an optional retryPolicy field to the atomic Get/Put/Delete query classes and to set these on the withRetryPolicy call. Then in autobatching code we can detect that these have been set and use this in the composite Batch query.