Fix misalignment in PodNamespaceSelector representation

[frapizzato]

Hello everyone,

This pull request addresses a parsing error in the REAR Controller caused by a misalignment between the internal and CRD representations of the PodNamespaceSelector.

The issue arises when the providers' Flavor resources include a non-empty value for the networkAuthorizations field, which is used for the intent-based border protection solution developed in WP5. In such cases, when a consumer retrieves the available resources as PeeringCandidates, a parsing error occurs in the consumer's REAR Controller, resulting in a null value for the networkAuthorizations field. The following reports the log entries illustrating the error:

E0527 14:30:47.059078       1 forge.go:809] Error when parsing resource selector from source destination
E0527 14:30:47.059085       1 forge.go:823] Error when parsing source from network intent
E0527 14:30:47.059100       1 forge.go:850] Error when parsing denied communication from network authorizations

To resolve the problem, the proposed PR aligns the two distinct representations in favor of a unified one, simplifying mapping operations and eliminating the parsing error.

Thanks,
Francesco

[LorenzoMoro]

LGTM