vapi: support api clients within vpp process

Add vapi_connect_from_vpp() and vapi_disconnect_from_vpp()
calls to allow API clients from within VPP process.

Add a new memclnt_create version that gives the user a
knob to enable or disable dead client scans (keepalive).

Type: feature
Signed-off-by: Ole Troan <ot@cisco.com>
Change-Id: Id0b7bb89308db3a3aed2d3fcbedf4e1282dcd03f
Signed-off-by: Ole Troan <ot@cisco.com>

test/test_api_client.py

@@ -0,0 +1,20 @@
+#!/usr/bin/env python3
+
+import unittest
+
+from framework import VppTestCase, VppTestRunner
+from vpp_ip_route import VppIpTable, VppIpRoute, VppRoutePath
+
+
+class TestAPIClient(VppTestCase):
+    """ API Internal client Test Cases """
+
+    def test_client_unittest(self):
+        """ Internal API client """
+        error = self.vapi.cli("test api internal")
+        if error:
+            self.logger.critical(error)
+            self.assertNotIn('failed', error)
+
+if __name__ == '__main__':
+    unittest.main(testRunner=VppTestRunner)