ipapwpolicy: Use global_policy if name is not set

If the name is not set, the policy global_policy is now used. It was needed
before to explicitly name the global_policy. Also a check has been added
to fail early if global_policy is used with state absent.

The README for pwpolicy has been extended with an example for global_policy
and also the description of the name variable.

The test has also been extended to check a change of maxlife for
global_policy and that global_policy can not be used with state: absent

Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1797532

tests/pwpolicy/test_pwpolicy.yml

@@ -5,10 +5,30 @@
   gather_facts: false
 
   tasks:
+  - name: Ensure maxlife of 90 for global_policy
+    ipapwpolicy:
+      ipaadmin_password: SomeADMINpassword
+      maxlife: 90
+
+  - name: Ensure absence of group ops
+    ipagroup:
+      ipaadmin_password: SomeADMINpassword
+      name: ops
+      state: absent
+
+  - name: Ensure absence of pwpolicies for group ops
+    ipapwpolicy:
+      ipaadmin_password: SomeADMINpassword
+      name: ops
+      state: absent
+
   - name: Ensure presence of group ops
     ipagroup:
       ipaadmin_password: SomeADMINpassword
       name: ops
+      state: present
+    register: result
+    failed_when: not result.changed
 
   - name: Ensure presence of pwpolicies for group ops
     ipapwpolicy:
@@ -42,6 +62,28 @@
     register: result
     failed_when: result.changed
 
+  - name: Ensure maxlife of 49 for global_policy
+    ipapwpolicy:
+      ipaadmin_password: SomeADMINpassword
+      maxlife: 49
+    register: result
+    failed_when: not result.changed
+
+  - name: Ensure maxlife of 49 for global_policy again
+    ipapwpolicy:
+      ipaadmin_password: SomeADMINpassword
+      maxlife: 49
+    register: result
+    failed_when: result.changed
+
+  - name: Ensure absence of pwpoliciy global_policy will fail
+    ipapwpolicy:
+      ipaadmin_password: SomeADMINpassword
+      state: absent
+    register: result
+    ignore_errors: True
+    failed_when: result is defined and result
+
   - name: Ensure absence of pwpolicies for group ops
     ipapwpolicy:
       ipaadmin_password: SomeADMINpassword
@@ -50,6 +92,13 @@
     register: result
     failed_when: not result.changed
 
+  - name: Ensure maxlife of 90 for global_policy
+    ipapwpolicy:
+      ipaadmin_password: MyPassword123
+      maxlife: 90
+    register: result
+    failed_when: not result.changed
+
   - name: Ensure absence of pwpolicies for group ops
     ipapwpolicy:
       ipaadmin_password: SomeADMINpassword