Add comprehensive unit tests for critical security components

- Added 15 tests for RolePrivilegeSetupService covering role and privilege initialization
- Tests for handling empty/null configurations and mixed existing/new entities
- Tests for database transaction handling and privilege reuse across roles
- Added 21 tests for CustomOAuth2AuthenticationEntryPoint
- Tests for OAuth2 and non-OAuth2 exception handling
- Tests for failure handler delegation and redirect behavior
- Tests for session handling and URL configuration
- All tests pass and provide real value testing actual business logic

Author: devondragon