SAAD: DDM Asset table migration

[MagnusHJensen]

Related issue: Resolves #48566

Checklist for submitter

If some of the following don't apply, delete the relevant line.

• Changes file added for user-visible changes in changes/, orbit/changes/ or ee/fleetd-chrome/changes.
  See Changes files for more information. Coming in bigger backend story.

• Input data is properly validated, SELECT * is avoided, SQL injection is prevented (using placeholders for values in statements), JS inline code is prevented especially for url redirects, and untrusted data interpolated into shell scripts/commands is validated against shell metacharacters.

• Timeouts are implemented and retries are limited to avoid infinite loops

• If paths of existing endpoints are modified without backwards compatibility, checked the frontend/CLI for any necessary changes

Testing

• Added/updated automated tests

• Where appropriate, automated tests simulate multiple hosts and test for host isolation (updates to one hosts's records do not affect another)

• QA'd all new/changed functionality manually

Summary by CodeRabbit

• New Features

  • Added support for tracking Apple declaration assets, including a new asset record and a link table for associating assets with declarations.
  • Added a new timestamp on declarations to reflect the latest asset update time.

• Bug Fixes

  • Strengthened database constraints to prevent duplicate asset entries and enforce valid asset/declaration references.
  • Improved delete behavior so referenced declarations clean up related links automatically.