Is your feature request related to a problem? Please describe.

Create an API to create a batch of jobs. All existing APIs only allow creating a single job at a time.

Describe the solution you'd like

(*jobs.Registry).CreateJobsWithTxn

Additional context

This is one of the remaining work items to fix #41930.

The relevant context is that today we create or update jobs eagerly during schema change operations in

Rather than creating these jobs eagerly, we should just store the intended job record in the extraTxnState and write it in one go before committing. This will be a major performance optimization for the existing code path and will be easy to adopt in the new schema changer.

Epic: CRDB-8577