Adjust generated delete method

[Andy2003]

The delete method for Nodes will have the following schema:

type Mutation {
  deleteMovies(where: MovieWhere): DeleteInfo!
}

type DeleteInfo {
  nodesDeleted: Int!
  relationshipsDeleted: Int!
}

Changes to the current implementation:

1. Return value is no longer the Deleted Entity
2. Multiple nodes can be deleted via the where-filter