Change exception types in network_segment_range
Change exception types in network_segment_range

This patch changes the exception types defined for network_segment_range
service plugin to ensure that they return Client Error (HTTP status code
4xx) to client.

Co-authored-by: Allain Legacy <Allain.legacy@windriver.com>

Partially-implements: blueprint network-segment-range-management
Change-Id: I4f2fbcbc7e88067e0cc7c3391cab7bf30fb39354

openstack/neutron-lib,openstack/neutron-lib,openstack/neutron-lib,openstack/neutron-lib