Set explicit confdir option for global contexts

Some API contexts are used to modify global state (e.g. files in /etc
and /var). These contexts do not support confdir overrides. Initialize
the API with an explicit confdir argument to paths.ETC_IPA.

The special contexts are:

* backup
* cli_installer
* installer
* ipctl
* renew
* restore
* server
* updates

The patch also corrects the context of the ipa-httpd-kdcproxy script to
'server'.

https://fedorahosted.org/freeipa/ticket/6389

Signed-off-by: Christian Heimes <cheimes@redhat.com>
Reviewed-By: Jan Cholasta <jcholast@redhat.com>

client/ipa-client-automount

@@ -384,6 +384,7 @@ def main():
 
     cfg = dict(
         context='cli_installer',
+        confdir=paths.ETC_IPA,
         in_server=False,
         debug=options.debug,
         verbose=0,