Add ability to disable apache modules

Introduce a new pillar apache:server:mods that is a dictionary with
the new module metadata. It will allow to manage apache modules by
setting "status: disabled/enabled".

Change-Id: I4ef85ce426f92e01a15e0fbcdb1370d68c1cf736
Related-Prod: PROD-23524
diff --git a/tests/pillar/apache_server_php7_ssl.sls b/tests/pillar/apache_server_php7_ssl.sls
index 8859b58..55c8264 100644
--- a/tests/pillar/apache_server_php7_ssl.sls
+++ b/tests/pillar/apache_server_php7_ssl.sls
@@ -30,6 +30,10 @@
       - dav
       - dav_fs
       - ssl
+    mods:
+      status:
+        enabled: True
+        status: 'disabled'
     module_php: php7.0
     user:
       cloudlab: