Parse async response in async action. (#16534)

* Parse async response in async action.
* Add async test for non-JSON data before module output.
* Fix existing async unit test.

Resolves #16156

test/integration/test_async.yml

@@ -0,0 +1,10 @@
+- hosts: testhost3
+  gather_facts: false
+  tasks:
+  # make sure non-JSON data before module output is ignored
+  - name: async ping with invalid locale via ssh
+    ping:
+    async: 3
+    poll: 1
+    register: result
+  - debug: var=result