New trust management module

There is a new trust management module placed in the plugins folder:
plugins/modules/trust.py
The trust module allows to ensure presence and absence of trusts.

Here is the documentation for the module:
README-trust.md

New example playbooks have been added:
playbooks/trust/add-trust.yml
playbooks/trust/del-trust.yml
New tests added for the module:
tests/hbacrule/test_trust.yml

playbooks/trust/add-trust.yml

@@ -0,0 +1,12 @@
+---
+- name: Playbook to create a trust
+  hosts: ipaserver
+  become: true
+
+  tasks:
+    - name: ensure the trust is present
+      ipatrust:
+        realm: windows.local
+        admin: Administrator
+        password: secret_password
+        state: present

playbooks/trust/del-trust.yml

@@ -0,0 +1,10 @@
+---
+- name: Playbook to delete trust
+  hosts: ipaserver
+  become: true
+
+  tasks:
+    - name: ensure the trust is absent
+      ipatrust:
+        realm: windows.local
+        state: absent