DNS forward policy: ensure consistency between module parameters.

Modules ipadnsconfig and ipadnsforwardzone allow the setting of forward
policy for zone forwarders, but the parameter names differ between the
modules.

This patch ensures that the same parameter names can be used in each
module. To keep backwar compatibility in both modules, both
`forward_policy` and `forwardpolicy` are now supported.

plugins/modules/ipadnsconfig.py

@@ -54,6 +54,7 @@ options:
       global forwarders.
     required: false
     choices: ['only', 'first', 'none']
+    alias: ["forwardpolicy"]
   allow_sync_ptr:
     description:
       Allow synchronization of forward (A, AAAA) and reverse (PTR) records.
@@ -189,7 +190,8 @@ def main():
             forwarders=dict(type='list', default=None, required=False,
                             options=dict(**forwarder_spec)),
             forward_policy=dict(type='str', required=False, default=None,
-                                choices=['only', 'first', 'none']),
+                                choices=['only', 'first', 'none'],
+                                aliases=["forwardpolicy"]),
             allow_sync_ptr=dict(type='bool', required=False, default=None),
 
             # general

plugins/modules/ipadnsforwardzone.py

@@ -68,7 +68,7 @@ options:
     required: false
     default: only
     choices: ["only", "first", "none"]
-    aliases: ["idnsforwarders"]
+    aliases: ["idnsforwarders", "forward_policy"]
   skip_overlap_check:
     description:
     - Force DNS zone creation even if it will overlap with an existing zone.
@@ -189,7 +189,8 @@ def main():
                                  port=dict(type='int', required=False,
                                            default=None),
                             )),
-            forwardpolicy=dict(type='str', aliases=["idnsforwardpolicy"],
+            forwardpolicy=dict(type='str',
+                               aliases=["idnsforwardpolicy", "forward_policy"],
                                required=False,
                                choices=['only', 'first', 'none']),
             skip_overlap_check=dict(type='bool', required=False),