Neutron: Move FWaaS OSC client code from neutronclient

Assisted-by: Claude-Code (claude-opus-4.6)
Change-Id: I7f7d737045ac30d5c5aca450e1a6d13ea3432fde
Signed-off-by: Slawek Kaplonski <skaplons@redhat.com>

Author: slawqo

openstackclient/network/client.py

@@ -23,7 +23,7 @@
 API_VERSION_OPTION = 'os_network_api_version'
 API_NAME = 'network'
 API_VERSIONS = ('2.0', '2')
-API_EXTENSIONS = ('taas',)
+API_EXTENSIONS = ('fwaas', 'taas')
 
 
 def make_client(instance):