authorized_keys - consistent behavior in check_mode

Previously check_mode would incorrectly return changed=False even when a
change would have taken place if ran without check_mode, with
integration tests that confirmed this incorrect behavior. Also the
module did not correctly populate the return values when run in
check_mode. Both of these issues are resolved in this PR.

Fixes https://github.com/ansible-collections/ansible.posix/issues/37

Signed-off-by: Adam Miller <admiller@redhat.com>

tests/integration/targets/authorized_key/tasks/main.yml

@@ -410,12 +410,13 @@
 # -------------------------------------------------------------
 # check mode
 
-- name: copy an existing file in place with comments
+- name: CHECK MODE | copy an existing file in place with comments
   copy:
     src: existing_authorized_keys
     dest: "{{ output_dir | expanduser }}/authorized_keys"
 
-- authorized_key:
+- name: CHECK MODE | add key in check mode to validate return codes
+  authorized_key:
     user: root
     key: "{{ multiple_key_different_order_2 }}"
     state: present
@@ -423,13 +424,21 @@
   check_mode: True
   register: result
 
-- name: assert that the file was not changed
+- name: CHECK MODE | assert that authorized_keys return values are consistent
+  assert:
+    that:
+      - 'result.changed == True'
+      - '"user" in result'
+      - '"key" in result'
+
+- name: CHECK MODE | recopy authorized_keys to ensure it was not changed 
   copy:
     src: existing_authorized_keys
     dest: "{{ output_dir | expanduser }}/authorized_keys"
   register: result
 
-- assert:
+- name: CHECK MODE | assert that the authorized_keys file was not changed
+  assert:
     that:
       - 'result.changed == False'