Fix CustomRole grants not persisting (SET ROLE to table owner)

[tmablunar]

Summary

• SyncDatabaseGrants and RevokeAllDatabaseGrants ran GRANT/REVOKE as iam_creator, which does not own the tables (service users like transactionrepo do). PostgreSQL requires the table owner to issue grants, so all grants silently failed.
• Added SET ROLE <owner> before each GRANT/REVOKE statement and RESET ROLE after, matching the pattern used by the PostgreSQLDatabase controller's execAsf/prependSetRole.
• Added schemaOwnerMap() and tableOwnerMap() helpers to bulk-query object ownership from pg_namespace and pg_tables.

Test plan

• Added TestSyncDatabaseGrants_grantsViaSetRoleToTableOwner — verifies GRANT and REVOKE succeed when connection user is a member of the table owner (SET only, no INHERIT)
• Added TestRevokeAllDatabaseGrants_viaSetRole — verifies RevokeAllDatabaseGrants works via SET ROLE
• Verified new tests fail without the fix (grants skipped with "permission denied") and pass with the fix
• All 23 existing CustomRole integration tests still pass

The key to making the test realistic was GRANT serviceUser TO controllerUser WITH SET TRUE, INHERIT FALSE. This mirrors production where iam_creator can SET ROLE to service users (via rds_superuser) but doesn't inherit their ownership privileges. Without INHERIT FALSE, PostgreSQL 18 lets members exercise all owner privileges including granting, which would mask the bug.

🤖 Generated with Claude Code

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Note

Medium Risk
Touches database privilege management logic and changes how SQL is executed (SET ROLE), which can impact access control behavior if owner detection or role membership is misconfigured.

Overview
Ensures SyncDatabaseGrants applies and removes schema/table privileges by first resolving schema/table owners and wrapping each GRANT/REVOKE (including schema USAGE) in SET ROLE <owner> ... RESET ROLE, so the controller can manage privileges on objects it doesn’t directly own.

Updates RevokeAllDatabaseGrants to revoke table privileges under all unique table owners in a schema (not just the schema owner), and adds integration tests covering SET ROLE behavior with INHERIT FALSE membership to match production.

^{Reviewed by Cursor Bugbot for commit 03332c8. Configure here.}