Add sonic-vxlan.yang to cvlyang-models (#22323)

How I did it
Added sonic-vxlan.yang to data_files.

Author: miatttao

src/sonic-yang-models/setup.py

@@ -276,6 +276,7 @@ def run(self):
                          './cvlyang-models/sonic-vnet.yang',
                          './cvlyang-models/sonic-vlan.yang',
                          './cvlyang-models/sonic-vrf.yang',
+                         './cvlyang-models/sonic-vxlan.yang',
                          './cvlyang-models/sonic-warm-restart.yang',
                          './cvlyang-models/sonic-lldp.yang',
                          './cvlyang-models/sonic-scheduler.yang',