19/02/2025 Update Unit Level Subscription Status Logic

Changes to the logic on subscription status. Ensuring correct functionality when the `preserve_consent` flag is used.

1. New locations for a given contact set the subscription status based on the request values passed in.

2. When a contact revisits a location, a contact stays subscribed when preserve consent rule is provided on the request.

3. Root ( head office ) units will always be subscribed.

4. Tested in a scenario where REST API attempts to merge multiple contacts down to one contact.

5. Additional error handling and fallbacks added where there are potential points of failure.

👨‍💻 Lee