##### SUMMARY
When specifying only action name and state "absent", that fails with "missing required arguments: event_source".
Zabbix action names are unique across types (event sources), thus the event source parameter in this case is not mandated by the Zabbix API.
It would be great to either lift this limitation, or add an example in the documentation explaining why it's there.

##### ISSUE TYPE
- Bug Report

##### COMPONENT NAME
zabbix_action

##### ANSIBLE VERSION
latest

##### CONFIGURATION
Not relevant.

##### OS / ENVIRONMENT
Not relevant.

##### STEPS TO REPRODUCE

```yaml
  - name: "Report problems to Zabbix administrators"
    state: absent
```

##### EXPECTED RESULTS
Either success, or documented special limitation.

##### ACTUAL RESULTS
```
failed: [host] (item={u'state': u'absent', u'name': u'Report problems to Zabbix administrators'}) => {"ansible_loop_var": "item", "changed": false, "item": {"name": "Report problems to Zabbix administrators", "state": "absent"}, "msg": "missing required arguments: event_source"}
```
self._module = module
        
        self._zapi_wrapper = zapi_wrapper
    def _construct_operationtype(self, operation):
        """Construct operation type.
        Args:
            operation: operation to construct
        Returns:
            str: constructed operation
        """
        try:
            return to_numeric_value([
                "send_message",
                "remote_command",
                "add_host",
                "remove_host",
                "add_to_host_group",
                "remove_from_host_group",
                "link_to_template",
                "unlink_from_template",
                "enable_host",
                "disable_host",
                "set_host_inventory_mode"], operation['type']
            )
        except Exception as e:
            self._module.fail_json(msg="Unsupported value '%s' for operation type." % operation['type'])
    def _construct_opmessage(self, operation):