Add code to be able to set default kinit lifetime

This is done by setting the kinit_lifetime option in default.conf
to a value that can be passed in with the -l option syntax of kinit.

https://pagure.io/freeipa/issue/7001

Signed-off-by: Simo Sorce <simo@redhat.com>
Reviewed-By: Pavel Vomacka <pvomacka@redhat.com>
Reviewed-By: Alexander Bokovoy <abokovoy@redhat.com>

pylint_plugins.py

@@ -69,6 +69,7 @@ fake_api_env = {'env': [
     'realm',
     'session_auth_duration',
     'session_duration_type',
+    'kinit_lifetime',
 ]}
 
 # this is due ipaserver.rpcserver.KerberosSession where api is undefined