feat: Support cross-namespace package references with PackageRef field

[evanwave]

Motivation

The current Function CRD uses a simple Package field to reference packages, which limits the ability to reference packages from different namespaces. This change introduces a new PackageRef structure that supports cross-namespace package references while maintaining backward compatibility and proper label management.

The main problems this solves:

1. Cross-namespace package references: Functions can now reference packages from different namespaces
2. Improved package label management: Package labels now include namespace information to avoid conflicts
3. Better validation: Enhanced webhook validation for cross-namespace references
4. Consistent labeling: Automatic generation of package labels with namespace prefix

Modifications

1. Updated Function CRD structure:

   • Replaced Package field with PackageRef structure containing Name and Namespace fields
   • Updated all test files to use the new PackageRef structure

2. Enhanced webhook validation:

   • Modified function_webhook.go to validate cross-namespace package references
   • Updated package label generation to include namespace prefix (format: namespace.package-name)
   • Added comprehensive tests for cross-namespace scenarios

3. Improved controller logic:

   • Updated function_controller.go to handle cross-namespace package lookups
   • Modified mapPackageToFunctions to work with namespace-aware package labels
   • Removed manual package label management from controller (now handled by webhook)

4. Enhanced test coverage:

   • Added extensive tests for cross-namespace package references
   • Updated existing tests to use PackageRef instead of Package
   • Added tests for automatic package label generation
   • Added integration tests for multiple functions with auto-generated labels

5. Updated package webhook:

   • Modified packages_webhook.go to use namespace-aware package labels when finding referencing functions

The changes maintain backward compatibility while providing a more robust and flexible package reference system that supports cross-namespace operations.