ipaautomountmap: add support for indirect maps

Indirect maps were not supported by ansible-freeipa ipaautomountmap.
This patch adds support for adding indirect automount maps using the
"parent" and "mount" parameters, if the map do not yet exist. An
existing map cannot be modified.

The "parent" parameter must match an existing automount map, and the
"mount" parameter is required if "parent" is used.

A new example playbook can be found at:

    playbooks/automount/automount-map-indirect-map.yml

A new test playbook was added to test the feature:

    tests/automount/test_automountmap_indirect.yml

README-automountmap.md

@@ -54,6 +54,21 @@ Example playbook to ensure presence of an automount map:
       desc: "this is a map for servers in the DMZ"
 ```
 
+Automount maps can contain a submount key, which defines a mount location within the map the references another map. On FreeIPA, this is known as an indirect map. An indirect automount map is equivalent to adding a proper automount key to a map, referencyng another map (this second map is the indirect map). Use `parent` and `mount` parameters to create an indirect automount map with ansible-freeipa, without the need to directly manage the automount keys.
+
+Example playbook to ensure an indirect automount map is present:
+
+```yaml
+---
+- name: Playbook to add an indirect automount map
+  ipaautomountmap:
+    ipaadmin_password: SomeADMINpassword
+    name: auto.indirect
+    location: DMZ
+    parent: auto.DMZ
+    mount: dmz_indirect
+```
+
 Example playbook to ensure auto.DMZi is absent:
 
 ```yaml
@@ -81,16 +96,14 @@ Variable | Description | Required
 `ipaadmin_password` | The admin password is a string and is required if there is no admin ticket available on the node | no
 `name` \| `mapname` \| `map` \| `automountmapname` | Name of the map to manage | yes
 `location` \| `automountlocation` \| `automountlocationcn` | Location name. | yes
+`parentmap` | Parent map of the indirect map. Can only be used when creating new maps. Default: auto.master | no
+`mount` | Indirect map mount point, relative to parent map. | yes, if `parent` is used.
 `desc` \| `description` | Description of the map | yes
 `state` | The state to ensure. It can be one of `present`, or `absent`, default: `present`. | no
 
 
-Notes
-=====
-
-Creation of indirect mount points are not supported.
-
 Authors
 =======
 
-Chris Procter
+- Chris Procter
+- Rafael Jeffman