feat: Add CloneRepositoryCredentials to Codebase spec

[zmotso]

Pull Request Template

Description

Add CloneRepositoryCredentials field to Codebase spec to support configurable repository credentials management. This replaces the hardcoded secret name pattern with a flexible reference-based approach.

The new field includes:

• secretRef: reference to credential secret
• clearSecretAfterUse: flag to control secret cleanup behavior

This change maintains backward compatibility by falling back to the legacy secret naming pattern when CloneRepositoryCredentials is not specified. The implementation includes comprehensive test coverage for various credential scenarios, including missing secrets, empty credentials, and secret retention policies.

Fixes #234

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Enhancement (non-breaking change which improves an existing feature or documentation)
• Breaking change (fix or feature that would cause existing functionality not to work as expected)

How Has This Been Tested?

• Unit tests
• Manually

Checklist:

• I have performed a self-review of my code
• I have commented on my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Pull Request contains one commit. I squash my commits.