Introduce a bulk option (or similarly named) option to updates and potentially destroys

Right now to do bulk mutations you need to wrap your `update` in a generic action and point graphql at the generic action since an update always just returns one record.

My proposal is a dsl modifier to the `update` and `destroy` graphql mappers that changes the return value to a list and executes a Bulk under the hood.

Start by locating the GraphQL mappers for update and destroy and the generic-action path used for bulk mutations. Clarify the DSL modifier's name and behavior, then verify that update and destroy can return lists and execute a Bulk operation, with coverage for both mutations.

Written by the indexing model from the issue text.