python/aqmp: Add dict conversion method to Greeting object

The iotests interface expects to return the greeting as a dict; AQMP
offers it as a rich object.

Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-id: 20210923004938.3999963-6-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>

python/qemu/aqmp/models.py

@@ -8,8 +8,10 @@ data to make sure it conforms to spec.
 # pylint: disable=too-few-public-methods
 
 from collections import abc
+import copy
 from typing import (
     Any,
+    Dict,
     Mapping,
     Optional,
     Sequence,
@@ -66,6 +68,17 @@ class Greeting(Model):
         self._check_member('QMP', abc.Mapping, "JSON object")
         self.QMP = QMPGreeting(self._raw['QMP'])
 
+    def _asdict(self) -> Dict[str, object]:
+        """
+        For compatibility with the iotests sync QMP wrapper.
+
+        The legacy QMP interface needs Greetings as a garden-variety Dict.
+
+        This interface is private in the hopes that it will be able to
+        be dropped again in the near-future. Caller beware!
+        """
+        return dict(copy.deepcopy(self._raw))
+
 
 class QMPGreeting(Model):
     """