[feature request]it is not appropriate to return Invalid in nodepool webhook

[rambohe-ch]

What would you like to be added:
In nodepool validation webhook, some fields in NodePool.Spec is not allowed to modify, but Invalid error code is returned. I think that it is appropriate to return Forbidden error code.

The following code lines should be modified:

openyurt/pkg/yurtmanager/webhook/nodepool/v1beta1/nodepool_validation.go

Line 61 in 4a96269

return apierrors.NewInvalid(appsv1beta1.GroupVersion.WithKind("NodePool").GroupKind(), newNp.Name, allErrs)

=> return apierrors.NewForbidden(appsv1beta1.GroupVersion.WithResource("nodepools").GroupResource(), np.Name, allErrs.ToAggregate())

openyurt/pkg/yurtmanager/webhook/nodepool/v1beta1/nodepool_validation.go

Line 74 in 4a96269

return apierrors.NewInvalid(appsv1beta1.GroupVersion.WithKind("NodePool").GroupKind(), np.Name, allErrs)

=> return apierrors.NewForbidden(appsv1beta1.GroupVersion.WithResource("nodepools").GroupResource(), np.Name, allErrs.ToAggregate())

openyurt/pkg/yurtmanager/webhook/nodepool/v1beta1/nodepool_validation.go

Line 124 in 4a96269

field.Invalid(field.NewPath("spec").Child("type"), spec.Type, "pool type can't be changed")})

=> field.Forbidden(field.NewPath("spec").Child("type"), "pool type can't be changed")})

openyurt/pkg/yurtmanager/webhook/nodepool/v1beta1/nodepool_validation.go

Line 129 in 4a96269

field.Invalid(field.NewPath("spec").Child("hostNetwork"), spec.HostNetwork, "pool hostNetwork can't be changed"),

=> field.Forbidden(field.NewPath("spec").Child("hostNetwork"), "pool hostNetwork can't be changed"),

Why is this needed:

others
/kind feature

[lilongfeng0902]

/assign @lilongfeng0902