Create api+scenario tests for healthmonitors

This patch implements healthmonitor tests for the Octavia
Tempest Plugin.

Depends-On: https://review.openstack.org/#/c/571107/
Change-Id: Ib7cd9eef7c9aeb705c56df3f88612d1bf2039163
Story: 2001387
Task: 5975
diff --git a/octavia_tempest_plugin/clients.py b/octavia_tempest_plugin/clients.py
index 7b766be..1bf1ebf 100644
--- a/octavia_tempest_plugin/clients.py
+++ b/octavia_tempest_plugin/clients.py
@@ -16,6 +16,8 @@
 from tempest import config
 
 from octavia_tempest_plugin.services.load_balancer.v2 import (
+    healthmonitor_client)
+from octavia_tempest_plugin.services.load_balancer.v2 import (
     listener_client)
 from octavia_tempest_plugin.services.load_balancer.v2 import (
     loadbalancer_client)
@@ -41,3 +43,5 @@
             self.auth_provider, SERVICE_TYPE, CONF.identity.region)
         self.member_client = member_client.MemberClient(
             self.auth_provider, SERVICE_TYPE, CONF.identity.region)
+        self.healthmonitor_client = healthmonitor_client.HealthMonitorClient(
+            self.auth_provider, SERVICE_TYPE, CONF.identity.region)