iotests.py: Adjust HMP kwargs typing

iotests.py: Adjust HMP kwargs typing

mypy wants to ensure there's consistency between the kwargs arguments
types and any unspecified keyword arguments. In this case, conv_keys is
a bool, but the remaining keys are Any type. Mypy (correctly) infers the
**kwargs type to be **Dict[str, str], which is not compatible with
conv_keys: bool.

Because QMP typing is a little fraught right now anyway, re-type kwargs
to Dict[str, Any] which has the benefit of silencing this check right
now.

A future re-design might type these more aggressively, but this will
give us a baseline to work from with minimal disruption.

(Thanks Kevin Wolf for the debugging assist here)

Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Message-id: 20201006235817.3280413-11-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>