New netgroup management module

There is a new netgroup management module placed in the plugins folder:

    plugins/modules/ipanetgroup.py

The netgroup module allows to ensure presence or absence of netgroup
and manage netgroup members.

Here is the documentation for the module:

    README-netgroup.md

New example playbooks have been added:

    playbooks/netgroup/netgroup-absent.yml
    playbooks/netgroup/netgroup-member-absent.yml
    playbooks/netgroup/netgroup-member-present.yml
    playbooks/netgroup/netgroup-present.yml

New tests for the module:

    tests/netgroup/test_netgroup.yml
    tests/netgroup/test_netgroup_client_context.yml
    tests/netgroup/test_netgroup_member.yml
    tests/netgroup/test_netgroup_member_absent.yml
    tests/netgroup/test_netgroup_member_case_insensitive.yml

Signed-off-by: Denis Karpelevich <dkarpele@redhat.com>

playbooks/netgroup/netgroup-absent.yml

@@ -0,0 +1,12 @@
+---
+- name: Netgroup absent example
+  hosts: ipaserver
+  become: no
+  gather_facts: no
+
+  tasks:
+  - name: Ensure netgroup my_netgroup1 is absent
+    ipanetgroup:
+      ipaadmin_password: SomeADMINpassword
+      name: my_netgroup1
+      state: absent

playbooks/netgroup/netgroup-member-absent.yml

@@ -0,0 +1,14 @@
+---
+- name: Netgroup absent example
+  hosts: ipaserver
+  become: no
+  gather_facts: no
+
+  tasks:
+  - name: Ensure netgroup user, "user1", is absent
+    ipanetgroup:
+      ipaadmin_password: SomeADMINpassword
+      name: TestNetgroup1
+      user: "user1"
+      action: member
+      state: absent

playbooks/netgroup/netgroup-member-present.yml

@@ -0,0 +1,13 @@
+---
+- name: Netgroup member present example
+  hosts: ipaserver
+  become: no
+  gather_facts: no
+
+  tasks:
+  - name: Ensure netgroup is present with user "user1"
+    ipanetgroup:
+      ipaadmin_password: SomeADMINpassword
+      name: TestNetgroup1
+      user: user1
+      action: member

playbooks/netgroup/netgroup-present.yml

@@ -0,0 +1,12 @@
+---
+- name: Netgroup present example
+  hosts: ipaserver
+  become: no
+  gather_facts: no
+
+  tasks:
+  - name: Ensure netgroup my_netgroup1 is present
+    ipanetgroup:
+      ipaadmin_password: SomeADMINpassword
+      name: my_netgroup1
+      description: My netgroup 1