feat(zone.xml): allow more services definition inside zone

Now multiple sections ending with `services` can be defined for each in pillar
and all of them will get merged into one service block in the zone. The goal is
to keep backward compatibility while allowing different services to be defined
in different pillars. So basically have various parts of the pillar affecting
the firewall without need to define everything centrally. Helpful for the
exceptions to the rules.

firewalld/files/zone.xml

     {%- endif %}
   {%- endfor %}
 {%- endif %}
-{%- if 'services' in zone %}
-  {%- for v in zone.services %}
+{%- for k,val in zone.items() %}
+  {%- if k.endswith("services") %}
+    {%- for v in val %}
   <service name="{{ v }}" />
-  {%- endfor %}
-{%- endif %}
+    {%- endfor %}
+  {%- endif %}
+{%- endfor %}
 {%- if 'ports' in zone %}
   {%- for v in zone.ports %}
     {%- if 'comment' in v %}

pillar.example

         are accepted.
       services:
         - http
-        - zabbixcustom
         - https
         - ssh
         - salt-minion
+      # Anything in zone definition ending with services will get merged into services
+      other_services:
+        - zabbixcustom
       protocols:
         - igmp
       rich_rules: