Re-visit restart policy and equivalent

[mangas]

Restart policy is now split between 2 places:

https://github.com/appvia/kev/blob/5a1c05c568427024fb3ef76a9fc0a5d6bdd1e341/pkg/kev/config/extensions.go#L187
https://github.com/appvia/kev/blob/5a1c05c568427024fb3ef76a9fc0a5d6bdd1e341/pkg/kev/converter/kubernetes/project_service.go#L408

and some really inconvenient assertions (IMO)
https://github.com/appvia/kev/blob/5a1c05c568427024fb3ef76a9fc0a5d6bdd1e341/pkg/kev/converter/kubernetes/project_service_test.go#L1052

A better way in my view would be to ensure all the logic for restart policy gets moved to extensions.go and that a type of errors gets introduced (e.g ErrUnsupportedRestartPolicy). This makes the separation between presentation and validation by making it possible to assert the error occurred and moving the output handling to the UI.