Wire postgres credentials into SOC module config

- Create vars/postgres.map.jinja for postgres auth globals
- Add POSTGRES_GLOBALS to all manager-type role vars
  (manager, eval, standalone, managersearch, import)
- Add postgres module config to soc/defaults.yaml
- Inject so_postgres credentials from auth pillar into
  soc/defaults.map.jinja (conditional on auth pillar existing)

salt/vars/postgres.map.jinja

@@ -0,0 +1,16 @@
+{# Copyright Security Onion Solutions LLC and/or licensed to Security Onion Solutions LLC under one
+   or more contributor license agreements. Licensed under the Elastic License 2.0 as shown at
+   https://securityonion.net/license; you may not use this file except in compliance with the
+   Elastic License 2.0. #}
+
+{% import 'vars/init.map.jinja' as INIT %}
+
+{%
+  set POSTGRES_GLOBALS = {
+    'postgres': {}
+  }
+%}
+
+{% if salt['file.file_exists']('/opt/so/saltstack/local/pillar/postgres/auth.sls') %}
+{%   do POSTGRES_GLOBALS.postgres.update({'auth': INIT.PILLAR.postgres.auth}) %}
+{% endif %}