Add ping_access_ip; allows to disable ping test (#7020)

In some environments, it might not be possible to ping the IP address
of the nodes, e.g., because ICMP echo is blocked.

This commit allows kubespray to be configured to disable the ping
check, while performing all other checks.

roles/kubernetes/preinstall/tasks/0020-verify-settings.yml

@@ -114,6 +114,7 @@
   when:
     - access_ip is defined
     - not ignore_assert_errors
+    - ping_access_ip
 
 - name: Stop if RBAC is not enabled when dashboard is enabled
   assert: