ipagroup: Fix management of AD objects

When using AD objects, a user expects to use the more human readable
form, like "user@ad.domain", but this impose some dificulties on
evaluating which object is being referenced as AD has several forms to
refer to the same object.

Each object is AD is identified uniquely by its SID, and this is the
identifier that IPA stores in its database. When managing AD objects,
IPA finds its SID and works with that value.

ansible-freeipa tried to process these objects using the human readable
values, and it cause idempontence error when ensuring the values were
present or modified, and, at least in some cases, prevented the objects
to be made absent, as the object list created didn't match the SID to
the value used as module parameter.

By using SID to process the AD objects in ipagroup, the addition or
removal of members works and idempotence of these members is ensured.

The only issue with thils approach is that it only works no server
nodes. In client nodes, the conversion to SID is not available and the
same issues that existed before will still be present.

Tests were updated to reflect these changes, a new test, specific to
idempotence issues of AD objects was added:

   tests/group/test_group_ad_users.yml

Resolves: https://issues.redhat.com/browse/RHEL-70023

README-group.md

@@ -8,8 +8,12 @@ The group module allows to ensure presence and absence of groups and members of
 
 The group module is as compatible as possible to the Ansible upstream `ipa_group` module, but additionally offers to add users to a group and also to remove users from a group.
 
-## Note
-Ensuring presence (adding) of several groups with mixed types (`external`, `nonposix` and `posix`) requires a fix in FreeIPA. The module implements a workaround to automatically use `client` context if the fix is not present in the target node FreeIPA and if more than one group is provided to the task using the `groups` parameter. If `ipaapi_context` is forced to be `server`, the module will fail in this case.
+
+Notes
+-----
+
+* Ensuring presence (adding) of several groups with mixed types (`external`, `nonposix` and `posix`) requires a fix in FreeIPA. The module implements a workaround to automatically use `client` context if the fix is not present in the target node FreeIPA and if more than one group is provided to the task using the `groups` parameter. If `ipaapi_context` is forced to be `server`, the module will fail in this case.
+* Using `externalmember` or `idoverrideuser` is only supported with `ipaapi_context: server`. With 'client' context, module execution will fail.
 
 
 Features
@@ -213,7 +217,7 @@ Example playbook to add members from a trusted realm to an external group:
 ---
 - name: Playbook to handle groups.
   hosts: ipaserver
-  
+
   tasks:
   - name: Create an external group and add members from a trust to it.
     ipagroup:
@@ -276,6 +280,7 @@ Example playbook to ensure groups are absent:
       state: absent
 ```
 
+
 Variables
 =========
 
@@ -299,8 +304,8 @@ Variable | Description | Required
 `service` | List of service name strings assigned to this group. Only usable with IPA versions 4.7 and up. | no
 `membermanager_user` | List of member manager users assigned to this group. Only usable with IPA versions 4.8.4 and up. | no
 `membermanager_group` | List of member manager groups assigned to this group. Only usable with IPA versions 4.8.4 and up. | no
-`externalmember` \| `ipaexternalmember`  \| `external_member`| List of members of a trusted domain in DOM\\name or name@domain form. | no
-`idoverrideuser` | List of user ID overrides to manage. Only usable with IPA versions 4.8.7 and up.| no
+`externalmember` \| `ipaexternalmember`  \| `external_member`| List of members of a trusted domain in DOM\\name or name@domain form. Requires "server" context. | no
+`idoverrideuser` | List of user ID overrides to manage. Only usable with IPA versions 4.8.7 and up. Requires "server" context. | no
 `rename` \| `new_name` | Rename the user object to the new name string. Only usable with `state: renamed`. | no
 `action` | Work on group or member level. It can be on of `member` or `group` and defaults to `group`. | no
 `state` | The state to ensure. It can be one of `present`, `absent` or `renamed`, default: `present`. | yes