Bulk create update

[tombch]

• This PR attempts to optimise the create endpoint by delegating 'nested' records to a bulk create rather than being created individually.
• It seems like an obvious thing to do, but I think before merging this PR it needs more investigation into potential ramifications of switching from creation via serializer to direct bulk creation.
• Bulk updates could also be useful if correctly added, and django-simple-history has support for this - currently not a feature though.

[Copilot]

Pull request overview

This pull request attempts to optimize the creation of nested objects by using bulk database operations instead of individual saves. The change modifies the _save method in SerializerNode to collect new nested instances and create them in bulk using bulk_create_with_history from the django-simple-history library.

Changes:

• Import bulk_create_with_history from simple_history.utils
• Modify nested object saving logic to distinguish between updates and creates
• Use bulk_create_with_history for creating multiple new nested objects at once

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.