Cross namespace references between `KongRoute` and `KongService`.

[pmalek]

Problem Statement

KongRoute's ServiceRef allows setting the referenced KongService.

This field allows setting namespace.

This task tracks the implementation of cross namespace references between KongRoute and KongService.

Proposed Solution

Additional Information

Acceptance Criteria

• As a user, I can reference a KongService from KongRoute in a different Namespace.