openssl_publickey: Ensure format OpenSSH is idempotent (#33264)

Currently the check() method for idempotence only assumes the public
key is under the form of a PEM file when its not always the case.

The module openssl_publickey allows one to generate OpenSSH format
publickey. This leads to idempotence not being detected.

test/integration/targets/openssl_publickey/tasks/main.yml

@@ -18,6 +18,14 @@
       # appeared in version 1.4 of cryptography
       when: cryptography_version.stdout is version('1.4.0', '>=')
 
+    - name: Generate publickey - OpenSSH format - test idempotence (issue 33256)
+      openssl_publickey:
+        path: '{{ output_dir }}/publickey-ssh.pub'
+        privatekey_path: '{{ output_dir }}/privatekey.pem'
+        format: OpenSSH
+      when: cryptography_version.stdout|version_compare('1.4.0', '>=')
+      register: publickey_ssh_idempotence
+
     - name: Generate publickey2 - standard
       openssl_publickey:
         path: '{{ output_dir }}/publickey2.pub'

test/integration/targets/openssl_publickey/tests/validate.yml

@@ -28,6 +28,12 @@
       - privatekey_publickey.stdout == '{{ publickey.content|b64decode }}'
   when: cryptography_version.stdout is version('1.4.0', '>=')
 
+- name: Validate public key - OpenSSH format - test idempotence (issue 33256)
+  assert:
+    that:
+      - not publickey_ssh_idempotence|changed
+  when: cryptography_version.stdout|version_compare('1.4.0', '>=')
+
 - name: Validate publickey2 (test - Ensure key has been removed)
   stat:
     path: '{{ output_dir }}/publickey2.pub'