feat: Identify all ressources by id_connection

[rflihxyz]

Phase 1, expand data model:

• [x] Add id_connection in all unified tables

Phase 2: Backfill data

Phase 3, collapse:

• [ ] Remove remote_platform and linked_user_id columns
• [ ] Rollout to dev, sandbox, prod
• [ ] close if no regression (check using git commit hash on sentry)