T4825: Add interface type veth

Add interface type veth (Virtual ethernet)
One of the usecases it's interconnect different vrf's and
default vrf via bridge

set interfaces virtual-ethernet veth0 peer-name 'veth1010'
set interfaces virtual-ethernet veth1010 address '10.0.0.10/24'
set interfaces virtual-ethernet veth1010 peer-name 'veth0'
set interfaces virtual-ethernet veth1010 vrf 'foo'
set interfaces bridge br0 address '10.0.0.1/24'
set interfaces bridge br0 member interface veth0

vyos@r1:~$ ping 10.0.0.10 count 1
PING 10.0.0.10 (10.0.0.10) 56(84) bytes of data.
64 bytes from 10.0.0.10: icmp_seq=1 ttl=64 time=0.082 ms

1 files changed, 39 insertions, 0 deletions

diff --git a/smoketest/scripts/cli/test_interfaces_virtual_ethernet.py b/smoketest/scripts/cli/test_interfaces_virtual_ethernet.py
new file mode 100755
index 000000000..b6f7db428
--- /dev/null
+++ b/smoketest/scripts/cli/test_interfaces_virtual_ethernet.py
@@ -0,0 +1,39 @@
+#!/usr/bin/env python3
+#
+# Copyright (C) 2023 VyOS maintainers and contributors
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License version 2 or later as
+# published by the Free Software Foundation.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+import os
+import unittest
+
+from vyos.ifconfig import Section
+from base_interfaces_test import BasicInterfaceTest
+
+class VEthInterfaceTest(BasicInterfaceTest.TestCase):
+    @classmethod
+    def setUpClass(cls):
+        cls._test_dhcp = True
+        cls._base_path = ['interfaces', 'virtual-ethernet']
+
+        cls._options = {
+            'veth0': ['peer-name veth1'],
+            'veth1': ['peer-name veth0'],
+        }
+
+        cls._interfaces = list(cls._options)
+        # call base-classes classmethod
+        super(VEthInterfaceTest, cls).setUpClass()
+
+if __name__ == '__main__':
+    unittest.main(verbosity=2)