[DT-3112] Add DELETE endpoint to Soft delete FileStorageObject

[kevinmarete]

Addresses

https://broadworkbench.atlassian.net/browse/DT-3112

Summary

This PR implements a soft delete endpoint for FileStorageObject (DELETE /api/{entity}/{entityId}/document/{id}), marking records as deleted without removing the underlying GCS blob. The change sets deleted, deleteUserId, and deleteDate fields while preserving audit history and enabling recovery.

Adds DAO support for soft deletion, enforces entity ownership and write access, and ensures idempotent behavior aligned with existing delete patterns. Also includes Swagger documentation and unit tests covering resource and DAO logic.

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[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
88.9% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[kevinmarete]

To be implemented in this PR: #2867