[k8s] Add base test for externaldns integration

- Add test for externaldns with coredns backend on basic
deployments.
- Add few core functions as remote executions of kubectl.

User-Story: https://mirantis.jira.com/browse/PROD-12826

Change-Id: I9230ddd75905759eb2d0ba8486ba896d2094cebb
diff --git a/tcp_tests/settings_oslo.py b/tcp_tests/settings_oslo.py
index 741a487..cc50762 100644
--- a/tcp_tests/settings_oslo.py
+++ b/tcp_tests/settings_oslo.py
@@ -278,7 +278,15 @@
     ct.Cfg('kubernetes_virtlet_enabled', ct.Boolean(),
            help="", default=False),
     ct.Cfg('kubernetes_virtlet_image', ct.String(),
-           help="", default='mirantis/virtlet:v0.7.0')
+           help="", default='mirantis/virtlet:v0.7.0'),
+    ct.Cfg('kubernetes_externaldns_enabled', ct.Boolean(),
+           help="", default=False),
+    ct.Cfg('kubernetes_externaldns_image', ct.String(),
+           help="", default='mirantis/external-dns:latest'),
+    ct.Cfg('kubernetes_externaldns_provider', ct.String(),
+           help="", default='coredns'),
+    ct.Cfg('kubernetes_coredns_enabled', ct.Boolean(),
+           help="", default=False)
 ]
 
 k8s_opts = [